Bitcoin’s circulating supply surpassed 20 million coins on March 9, a milestone that places 95% of all BTC that will ever exist into the hands of holders and leaves fewer than 1 million coins still to be mined before the network reaches its hard cap of 21 million.
The milestone was reached at block height 940,000, with the block mined by Foundry USA, according to Mempool data.
It took roughly 17 years for miners to produce those first 20 million coins. The final 1 million will take more than a century to enter circulation, with the last fractions, measured in units called satoshis, expected to be issued around 2140.
Thomas Perfumo, chief economist at the exchange Kraken, framed the milestone in terms of Bitcoin’s design philosophy, saying:
“In a world of excess and abundance, Bitcoin stands as one of the few truly scarce assets. Unlike traditional currencies with unlimited supply, Bitcoin’s maximum supply is mathematically bound.”
Simon Gerovich, founder of Japan-based Metaplanet, offered a more succinct view, noting that the remaining 1 million BTC would represent “the era [when] true digital scarcity [begins].”
Both men represent firms with significant financial exposure to Bitcoin, and their optimism should be read accordingly. Kraken generates revenue from Bitcoin trading, and Metaplanet holds Bitcoin as a core treasury asset.
The milestone, however, is independently verifiable on the blockchain, and the supply mechanics underlying their claims are written into open-source code that has operated without interruption since 2009.
Shrinking subsidies push miners toward new business models
Bitcoin’s issuance schedule has always been front-loaded by design. When the network launched, miners received 50 BTC for each block they validated. That reward fell to 25 BTC in 2012, to 12.5 BTC in 2016, to 6.25 BTC in 2020, and to 3.125 BTC after the fourth halving in April 2024.
Each halving occurs every 210,000 blocks, roughly every four years, on a schedule that no government, central bank, or corporate issuer can unilaterally alter.
The economic consequences of that tightening supply schedule fall first and hardest on miners. Every halving strengthens the scarcity argument for holders while simultaneously cutting the stream of newly minted coins that compensates the operators who secure the network.
That pressure is showing up in real time. Hashprice, a metric that measures daily mining revenue per unit of computational power, fell below $30 per petahash per second per day in late February after a sharp increase in network difficulty.
Hashrate Index reported that levels around $30 sit at or below breakeven for many operators even before broader corporate overhead is factored in.
Transaction fees have so far offered limited relief. Hashrate Index said miners collected an average of 0.0192 BTC in fees per block during the past week.
Against a block subsidy of 3.125 BTC, that leaves miner revenue overwhelmingly dependent on the subsidy and on Bitcoin’s market price. The fee market remains too thin, at least at present, to cushion the step-down in block rewards.
That strain is accelerating a split within the mining industry. One camp is doubling down on Bitcoin production, pursuing greater machine efficiency, more favorable power contracts, and larger operational scale.
The other camp is reframing mining sites as energy and cooling infrastructure that can serve higher-margin computing workloads, particularly artificial intelligence and high-performance computing.
For context, several publicly traded miners, including Core Scientific, Bitfarms, TeraWulf, CleanSpark, and Hut 8, have announced AI pivots over the past year.
During this period, these companies have reportedly announced more than $43 billion in AI and high-performance computing contracts.
The long shadow over network security
The migration of well-capitalized miners toward AI hosting raises a question the Bitcoin community has debated for years but can no longer treat as distant: how will the network sustain enough computational power to remain secure as the block subsidy continues its programmed decline toward zero?
Bitcoin’s security model relies on miners’ energy and computational resources to validate transactions and add blocks to the chain. In return, they receive the block subsidy and transaction fees.
The subsidy has historically accounted for the vast majority of that compensation. As halvings continue to cut that subsidy in half roughly every four years, the model assumes that transaction fees will eventually grow large enough to replace it.
So far, the evidence supporting that assumption is thin. Fee revenue remains a small fraction of total miner income, and the gap between subsidy income and fee income has widened, even as Bitcoin’s price has recently struggled despite its rising adoption.
Justin Drake of the Ethereum Foundation argued in 2025 that Bitcoin’s fees have not risen enough to compensate for successive halvings and warned that persistently low fee revenue could compromise long-run security.
According to him:
“Bitcoin’s security model is broken. If Bitcoin gets taken over, the fallout could take the entire crypto ecosystem with it. The systemic risks can’t be ignored.”
Notably, his critique reflects a structural concern that Bitcoin developers and economists have also acknowledged internally.
The counterargument within Bitcoin circles rests on two assumptions. The first is that a rising Bitcoin price will keep mining profitable even as the per-block subsidy declines in BTC terms, because the fiat-denominated value of each coin will offset this decline.
The second is that the fee market will mature as more users and institutions transact on the network and on layers built on top of it, such as the Lightning Network and emerging protocols for tokenized assets.
Whether those assumptions hold will play out over decades. The 20 million coin milestone, meanwhile, offers a clear snapshot of where Bitcoin stands in that transition.
The overwhelming majority of its supply now exists. The dilution rate is already low and locked into a schedule that will push it lower still. Institutional adoption through exchange-traded funds, corporate treasuries, and professional capital allocations has broadened the demand base considerably over the past two years.
For holders, that combination of constrained supply and widening demand channels is the core investment thesis. For miners, the same supply mechanics that underpin that thesis are compressing margins and forcing strategic reinvention.
And for the network itself, the open question is whether the fee market and Bitcoin’s price trajectory can sustain the security infrastructure that keeps the entire system functioning, long after the last coin is mined, more than a century from now.