Game Theory and Bitcoin: the Miners’ Perspective

Competition drives markets. In traditional financial markets, however, competition is limited to the production of goods and the buying and selling process. With Bitcoin, competition plays a far-deeper role. The minting of new bitcoin, as well as the processing and verification of transactions, are all made more efficient, accurate, and secure, thanks to competition. It’s no surprise, then, that game theory plays a pivotal role in the inner workings of the Bitcoin ecosystem.

A brief explanation of game theory

Game theory models the strategic interaction between players in a scenario with set rules and outcomes where the players are rational and looking to maximize their payoffs. In effect, it’s a more detailed, nuanced way of looking at how incentives affect how things get done.

For example, if your job is to shovel 100 pounds of stone into a hole and you’re all alone and have all the time you want, there’s no game theory involved. On the other hand, if someone else is given the same task and you’re each working with the same pile of stones, the dynamics of the situation change.

They change further if only the person who shovels the most gets paid. And, naturally, if you get paid according to how much you shovel, the outcome of your actions would change in yet another way. Each of these situations will be impacted by game theory and its many models.

Although Bitcoin seeks to espouse concepts like “fairness,” “transparency,” and others that are often incongruent with competition, game theory still plays a primary role in the Bitcoin universe.

How does game theory apply to Bitcoin mining?

Bitcoin mining involves solving math problems that are used to create new bitcoin and verify transactions. To continue with the stone shoveling example, if you have as long as you want to move the pile of stones, you may choose to take your time. Your shovel may move slower than if someone else were involved in the task because then the speed at which you shovel would determine whether you get paid more, less, or at all.

The fact that multiple miners compete to verify transactions and generate coins gives Bitcoin an inherent efficiency: The job gets done faster. To dig a little deeper, three types of game theory driving this process include zero-sum theory, congestion theory, and the Nash equilibrium. Let’s take a closer look at how these concepts work.

Bitcoin mining and zero-sum theory

Zero-sum theory dictates that the “winner” gets the spoils and everyone else walks away with nothing. In the mining of bitcoin, the first person to solve a problem gets the value associated with completing the task. Everyone else gets nothing. If you could take a snapshot of the nanosecond a particular hash is found, you would see one user getting rewarded for their work and the others getting nothing.

However, because the Bitcoin system requires so many problems to be solved all the time, in reality, many miners can earn a relatively steady income. The strategies they use are governed by two other game theory concepts — the congestion theory and the Nash equilibrium.

Bitcoin mining and congestion theory

Congestion theory stipulates that the amount each player gets depends on the resources they choose and how many other players choose the same resources.

For example, imagine there are two stations with trains heading to the same destination, and each train can hold only 10 people. One train station is five miles closer to the destination. If there are 100 people, and everyone goes to the closer station, one train will have to go back and forth 10 times. On the other hand, if some of the passengers go to the closest station and others go to the station farther away, there will be less congestion, and everyone will arrive at the destination sooner.

In Bitcoin mining, many of the decisions of the miners depend on congestion theory. If there was only one miner, all the spoils would go to her or him. On the other hand, Bitcoin is open to all, so each miner has to decide whether they will get in the game — and add to the congestion — knowing that more people are bound to get in the game, decreasing their chance of winning.

Once a miner decides to get involved, they then have other decisions to make regarding the equipment they choose. Faster equipment provides an advantage, similar to getting on the closer train. However, the quicker the equipment, the more electricity it takes to run, which increases the cost of mining.

If a miner’s earnings won’t sufficiently offset the cost of electricity, they may choose not to get involved. They may also choose to forego setting up a mining system and join a mining pool instead, where the electricity costs are absorbed by multiple participants. Congestion theory dictates which “train” each miner takes, as well as when and how they get involved.

In addition, the way the decisions of each miner affects the others is governed largely by another game theory concept: the Nash Equilibrium.

Bitcoin mining and the Nash Equilibrium

In the Nash equilibrium, named after mathematician John Nash from the movie A Beautiful Mind, each “player” recognizes that while they have similar goals, not everyone can get exactly what they want. Therefore, some will choose to settle for a less-desirable outcome, satisfied with the fact that they are at least getting something. All players agree to proceed, happy to share the spoils.

For example, continuing with the stone shoveling scenario, you may be stronger and faster than the other shoveler. Both of you agree to shovel for the same amount of time, but you get 70% of the money while the other shoveler only gets 30%. The other person could protest, but realizing that something is better than nothing, they agree to the terms. At this point, an equilibrium is established. At the end of the day, you both earn money and walk away satisfied.

The worldwide community of miners also follows Nash equilibrium principles. Some miners have more money than others and can afford to purchase the latest mining computers, capable of solving specific hashes faster than older models. Other miners may not have as much money, but they live in areas where electricity is less expensive. They can, therefore, spend less than wealthier miners who live in areas where electricity is more costly. Some live in places where it will never be profitable to mine, so they join a mining pool instead.

Each miner recognizes that their limitations dictate how much they will get. At the same time, all agree to participate, satisfied with their portion at the end of the day — even if it’s just a small fraction of a bitcoin.

How miners are incentivized

Zero-sum theory, congestion theory, and the Nash equilibrium only work because of the ways miners are incentivized and dissuaded from cheating the system. Before mining rewards are approved, the technical infrastructure enforces the “trustless” nature of the Bitcoin network. If miners do not adhere to protocol rules, their block submission will be rejected by other nodes in the blockchain. All network nodes including other miners verify the ledger entries packaged into a new block. If entries are considered invalid, or the block hash doesn’t meet network requirements, the miner’s result will be rejected and the 6.25 BTC will be awarded to another miner.

While the block rewards are enticing at current BTC valuations, there are other financial implications that compel miners to either continue or suspend network operations. No miner will win the worldwide competition each time a new block is added (~every 10 minutes), so they must weigh the probability of profitable successes. There are other factors to consider, too. For example, some miners may decide to bow out when electricity becomes too expensive. Others however, may have a longer time horizon and decide to accept the risk of energy expenditure, calculating that miner attrition will increase their chances of winning new block rewards. In other words, fewer miners in the network means more chances for the remaining miners to profit. For those adopting this viewpoint, the potential of solving enough blocks to maintain business profitability outweighs the risk of any short-term loss related to high energy costs.

How bitcoin is distributed

Every block consists of many small transactions. When a block is mined, the winning miner is awarded 6.25 bitcoin plus all transaction fees for each transaction they were able to package within the block. The more blocks you are able to solve, the higher your reward. In other words, you get a bigger piece of the pie. Hunger for more slices of pie incentivizes miners to purchase more powerful equipment or move to areas with lower electricity costs.

Game theory and the surety of the Bitcoin network

The Nash equilibrium helps motivate miners to do more than generate new bitcoin. Each miner has no choice but to play a role in making sure the network functions as it should. This is a part of the “pile of stones” each miner agrees to shovel.

In a Nash equilibrium, although the individual participants would like to either get more rewards or a different type of reward, they agree to settle with getting something of value rather than nothing. The Bitcoin network compels miners to play by an agreed set of rules to add transactions to the distributed ledger, or their work will be summarily rejected. At the same time miners add security to the network by expending expensive energy that chains each new block to the preceding block via a well established mathematical algorithm.

Each miner is, therefore, a generator of new bitcoin liquidity as well as an auditor, checking the details of network transactions. Even though each problem solved involves a zero-sum game and congestion theory dictates how each miner approaches the task, everyone works in a happy Nash equilibrium.

In the end, game theory is an underestimated, yet essential, element of the Bitcoin network. As each miner plays their role, historical transactions are kept secure and new transactions unanimously approved, which helps maintain Bitcoin’s position as the number one digital currency in the worldC

 

Halve you heard? Your Guide to Bitcoin Halving Events

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While the world’s fiat currencies suffer from inflation as governments print more money to manage the COVID-19 crisis, Bitcoin, by design, is becoming more deflationary with each block confirmation. This is because Bitcoin creator Satoshi Nakamoto intended for Bitcoin to be the antithesis of government-controlled fiat currencies: “The root problem with conventional currency is all the trust that’s required to make it work,” wrote Satoshi in a post on the P2P Foundation Forum, “The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust.” In the post, dated February 11, 2009, Satoshi announces the creation of Bitcoin (along with a link to the earlier published white paper) and details its characteristics that make it anything but conventional. Among these characteristics is the fact that “everything is based on crypto proof instead of trust.”

In creating Bitcoin as a decentralized, trustless system, Satoshi ensured that it could not fall victim to the “breaches of trust” and inflation experienced throughout the history of fiat currencies. Unlike fiat currencies that are controlled and manipulated by governments and central authorities, Bitcoin follows a strict set of rules that have been embedded into its codebase or “monetary policy” since its inception. These rules include a hard supply limit of 21 million coins, the last of which will be mined around the year 2140. Currently, more than 87 percent of the 21 million bitcoin have been mined, meaning there are approximately 3 million remaining coins to be mined over the course of the next 120 years. The speed at which new bitcoin is mined and distributed is controlled by 30 precoded “halving” or “halvening” events (our Twitter followers prefer “halving”, so we’ll go with that from now on) that will take place every 210,000 blocks or about every four years until the last bitcoin is mined. In 2008 the block reward for miners was 50 newly minted bitcoin for each validated block. Following the first halving event in 2012, the block reward reduced by 50 percent to 25 bitcoin per validated block and then reduced by another 50 percent to 12.5 bitcoin following the second halving event in 2016. 2020 marks the year for the third halving event in which the block reward will be reduced to 6.25 bitcoin per validated block.

While we don’t know the exact date of the halving event (more on this below), we know it is fast approaching and is set to occur sometime this month. There’s been a lot of anticipatory chatter about the halving as people question and speculate on how it will (or will not) impact everything from the price of bitcoin to profitability and participation of miners in the network.

We’ve compiled what we consider to be the best available resources for understanding the Bitcoin 2020 Halving event and answering some of the most common questions around it.

When will the halving occur?

The answer to this question is contingent on the speed at which new blocks are created. Given the average block time is around 10 minutes and a halving event takes place every 210,000 blocks, the halving is estimated to occur on or around May 11. While there are various countdown resources that estimate within a day of one another, our favorites are the Bitcoin Halving Countdown from CoinMarketCap and the Bitcoin Clock, which “uses data from BTC.com to get the average block time for the past two months. It then uses this block time (currently 10.3125 minutes between blocks as of March 25, 2020) to estimate the halving date.”

Tell me more about the halving. What is it exactly? What is the intention behind it?

Whether you’re new to crypto or you’ve been in the game for years, we can all use a bit of a refresher when it comes to the halving event. If you’re new to crypto, we recommend starting with this video from We Use Coins regarding the need for Bitcoin and this video from CryptoCasey, which provides a straightforward explanation of blockchain technology, mining, and the upcoming bitcoin halving event. For a more humorous take on the benefits of “the currency of the future,” check out this video from Cameralla Comedy.

Running short on time? Try this episode of the 4-Minute Crypto Show, which offers a speedy, yet thorough explanation of halving events.

If you’re already familiar with the crypto basics and want more detail on the halving, this article from CoinDesk is an excellent resource. Not only does it include an illustrative explainer video that breaks down and simplifies the process, but the article also dives into:

  • the economic reasoning behind Satoshi’s decision to build the halving events into Bitcoin’s code

For additional info on previous halving events and miners’ roles in the network, Michael Sweeney from The Block provides a solid explanation in his analysis, “The bitcoin halving: what it is and why it matters.”

Interested in learning more about the economics behind Bitcoin’s monetary policy? Take a look at this article from The Block’s Mike Orcutt or this guide from Block Geeks that provides a crash course on supply and demand, inflation, deflation, and market cap as it relates to bitcoin, as well as how incentivization for miners fits into the equation. Or if you really want to get into it, Bitcoin Magazine’s Peter C. Earle explains why the 2020 halving is particularly important. He calls out the difference between the old and modern definitions of inflation, noting that in the context of the modern definition which refers to “an increase in general price levels within an economy,” the fact that “with increasing value one bitcoin buys more over time, it is indisputably deflationary.”

“What’s noteworthy about this point, Earle writes, “is that, upon this particular halving, Bitcoin ‘inflating’ at a roughly 1.8 percent rate annually will nominally — and by then, quite possibly in real terms — be ‘inflating’ at a rate lower than both the Federal Reserve target of 2 percent per year and current, CPI-based estimates of real U.S. inflation of 1.9 percent annually.”

Tell me more about the miners. How will it impact who is currently mining and who will continue to profit? Will the halving result in mining eventually becoming monopolized?

Andreas Antonopoulos tackles these questions in this short video clip and notes that we don’t need to be concerned about the monopolization of mining because the amount of profit a miner generates is not contingent on the size of their mining facility but on the smoothness of their mining operation. So while there are multiple factors that play into whether a mining operation is profitable, larger operations do not necessarily have an advantage over smaller ones. Rather, it’s all about efficiency. “Halving will increase competition in mining,” he says, and in general it will be the least efficient miners that become less profitable.

Similarly, in an interview with Anthony Pompliano the CEO of Blockware Solutions Matt D’Souza states, “The efficient miner should not fear the halving, they should welcome it.” Why? D’Souza notes that “once we go through halving the miners’ revenue is going to get slashed in half” and we’re going to experience what he considers to be “a healthy cleanse of the network.” He predicts that if the bitcoin price is still at $8k or lower going into the halving, we may experience “extreme miner capitulation” where we may see up to 40 percent of the network shutting off due to high energy costs and reliance on outdated mining equipment. He notes that as these inefficient miners begin to pull out of the network following the halving, there will be an adjustment period from May to July as the network undergoes these changes. At that point, difficulty will kick in and margins will improve for those miners who are still in the game. “Mining is about survivability,” says D’Souza, “You just need to survive. If you survive, difficulty will adjust in the future and it’s going to improve your margins because the people that are inefficient… their bitcoin is going to go to you.”

What happens to miners once all of the bitcoin has been mined and there are no more block rewards?

After the final halving event takes place and the 21 millionth bitcoin is mined sometime in 2140 miners will no longer receive block rewards, but they will still collect transaction fees just as they do currently. While we don’t know for sure how miners will react once we reach this point, according to Adam Barone in his article published on Investopedia, “Even when the last bitcoin has been produced, miners will likely continue to actively and competitively participate and validate new transactions. The reason is that every bitcoin transaction has a small transaction fee attached to it. These fees, while today representing a few hundred dollars per block, could potentially rise to many thousands of dollars or more per block as the number of transactions on the blockchain grows and as the price of a bitcoin rises. Ultimately, it will function like a closed economy where transaction fees are assessed much like taxes.”

What about the bitcoin price? How will it be impacted by the halving event?

The short answer is that there is no shortage of predictions.*

To quote Antonopoulos regarding his thoughts on price predictions: “I think it’s mostly irresponsible to make predictions about price. It’s the same as astrology and reading tea leaves.” While we agree with him on this sentiment, many people in the cryptosphere have openly made predictions about what will happen to the price of bitcoin following the 2020 halving. So, if you’re one for speculation or you just find it fun to read about people’s theories and want to be aware of what some of the most well-known people in the industry are saying, here are a few links for you to check out:

How can I watch the halving event?

For the previous halvings, it was fairly common for people to throw watch parties to celebrate the halving event. Now with current social distancing measures in place, in-person parties are being replaced by live streams. Our pick for how to watch and celebrate the 2020 Halving is Bitcoin Magazine’s 21-hour Live Stream for which they’ll be sharing updates across their social channels regarding exact timing, but you can track their countdown here.

*This content is meant to educate and inform but should not be taken as financial or investment advice. Trading and investing in cryptocurrencies (also called digital or virtual currencies, cryptoassets, altcoins and so on) involves substantial risk of loss and is not suitable for every investor.

Our Two Satoshis on the 10th Anniversary of Bitcoin

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Ten years ago today Satoshi Nakamoto announced his vision to change the world. This vision came via the Bitcoin White paper, which defined Bitcoin as “A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution.” Since the publishing of the white paper, Bitcoin has completely revolutionized the way we think about the world — not only in how the world works today, but in how it can work in the future.

As we acknowledge the tenth anniversary of Satoshi’s white paper, we at SALT are proud to not only be contributors to the blockchain space, but to be among those working to advance the capabilities of humanity via blockchain. Ten years later and Satoshi’s work is still inspiring people throughout the world — it’s the catalyst for individuals and companies to find new ways of addressing challenges with global finance, real estate, and healthcare, to tracking everything from global food supply, to votes to donations. It’s not just a new technology but a new way of thinking — and one thing’s for sure — SALT wouldn’t exist without it.

To commemorate this moment in time, we spoke with SALT’s team and clients about what Bitcoin means to them, how it’s impacted their lives, and how it’s changed the world. Here’s what they had to say:

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The first card powered by your crypto,
not your credit score.

The first card powered by your crypto,
not your credit score.

Three SALT credit cards floating