Bitcoin’s circulating supply surpassed 20 million coins on March 9th, a milestone in which 95% of all BTC in existence will be in the hands of holders, with less than 1 million coins still to be mined before reaching the network’s hard cap of 21 million.
According to Mempool data, the block mined by Foundry USA reached the milestone with a block height of 940,000.
It took miners approximately 17 years to produce the first 20 million coins. It will be more than a century before the last million copies enter circulation, and the last fraction, measured in units called satoshis, is expected to be issued around 2140.
Thomas Perfumo, chief economist at exchange Kraken, framed this milestone in terms of Bitcoin’s design philosophy:
“In a world of excess and abundance, Bitcoin is one of the few truly rare assets. Unlike traditional currencies, which have an unlimited supply, the maximum supply of Bitcoin is mathematically limited.”
Simon Gerovich, founder of Japan-based MetaPlanet, offered a more succinct view, noting that the remaining 1 million BTC represents “the beginning of a true digital scarcity era.”
Both represent companies with significant financial exposure to Bitcoin, and their optimism should be read accordingly. Kraken generates revenue from Bitcoin transactions, and Metaplanet holds Bitcoin as its core financial asset.
However, this milestone is independently verifiable on the blockchain, and the supply mechanism underlying their claims is written in open source code and has been operating without interruption since 2009.
Reduced subsidies will push miners towards new business models
Bitcoin’s issuance schedule has always been pushed forward by design. Once the network was launched, miners received 50 BTC for each block they verified. That reward decreased to 25 BTC in 2012, 12.5 BTC in 2016, 6.25 BTC in 2020, and 3.125 BTC after the fourth halving in April 2024.
Each halving occurs every 210,000 blocks, roughly every four years, and the schedule cannot be changed unilaterally by governments, central banks, or corporate issuers.
The economic impact of tight supply schedules will fall first on miners. Each halving strengthens the scarcity argument for holders, while also cutting off the flow of newly minted coins that rewards operators for protecting the network.
That pressure is manifesting itself in real time. Hashprice, a metric that measures daily mining revenue per unit of computing power, fell below $30 per petahash per second per day in late February as network difficulty increased sharply.
The Hashrate Index reports that levels around $30 remain below the break-even point for many carriers, even before considering a company’s broader overhead costs.
Transaction fees have so far provided limited relief. According to Hashrate Index, miners collected an average of 0.0192 BTC in fees per block last week.
For a block subsidy of 3.125 BTC, the miner’s revenue will overwhelmingly depend on the subsidy and the market price of Bitcoin. At least for now, the fee market remains too thin to cushion block reward cuts.
That strain is accelerating divisions within the mining industry. One camp is doubling Bitcoin production, pursuing higher mechanical efficiency, more favorable power contracts, and greater operational scale.
The other camp seeks to reconfigure mining sites as energy and cooling infrastructure capable of supporting high-margin computing workloads, particularly artificial intelligence and high-performance computing.
By way of background, several publicly traded miners have announced transformations to AI over the past year, including Core Scientific, Bitfarms, TeraWulf, CleanSpark, and Hut 8.
During this period, these companies reportedly announced more than $43 billion in AI and high-performance computing deals.
The long shadow that hangs over network security
The move of well-capitalized miners to AI hosting raises questions that the Bitcoin community has been discussing for years but can no longer be treated as distant. How will the network maintain enough computational power to remain secure as block subsidies continue to decline systematically towards zero?
Bitcoin’s security model relies on the energy and computational resources of miners to validate transactions and add blocks to the chain. In return, they receive block subsidies and transaction fees.
Subsidies have historically made up the bulk of that compensation. As subsidies continue to halve approximately every four years, our model assumes that transaction fees will eventually become large enough to replace them.
So far, there is little evidence to support that assumption. Fee income remains a small portion of miners’ total revenue, and the gap between subsidy income and fee income is widening, even as Bitcoin’s price has slumped recently despite increasing adoption.
Justin Drake of the Ethereum Foundation argued in 2025 that Bitcoin fees have not risen enough to compensate for successive halvings, warning that persistently low fee income could undermine long-term security.
According to him:
“Bitcoin’s security model is broken. If Bitcoin is compromised, the fallout could engulf the entire cryptocurrency ecosystem. The systemic risk cannot be ignored.”
Notably, his criticism reflects structural concerns acknowledged internally by Bitcoin’s developers and economists as well.
The counterargument in the Bitcoin world is based on two assumptions. First, the increase in Bitcoin prices will keep mining profitable even as the per-block subsidy decreases in BTC terms, as the fiat value of each coin offsets this decline.
The second is that the fee market will mature as more users and institutions transact on the network and on the layers built on top of it, such as the Lightning Network and emerging protocols for tokenized assets.
Whether these assumptions hold will become clear over the coming decades. On the other hand, the 20 million coin milestone clearly indicates Bitcoin’s position in that transition period.
The vast majority of that supply currently exists. Dilution rates are already low and are locked into a timeline for further reductions. Adoption by institutional investors through exchange-traded funds, corporate treasury, and professional capital allocation has significantly expanded the demand base over the past two years.
For holders, the combination of constrained supply and expanding demand channels is the core theory of investment. For miners, the same supply mechanisms that underpin that theory are compressing margins and forcing strategic reinvention.
And an open question for the network itself is whether the fee market and Bitcoin price movement can maintain the security infrastructure that keeps the entire system functioning more than a century after the last coin was mined.
