Bitcoin's supply famously halves roughly every four years. Less well-known is that these scheduled reductions will continue for well over a century.

Satoshi Nakamoto, Bitcoin's mysterious creator, programmed the year 2140 – 120 years from now – as the endpoint. By then, block rewards (miner payouts for processing transactions) will fall below a single satoshi, the smallest Bitcoin unit (0.00000001 BTC).

The term "satoshi" emerged organically among early Bitcoin users around 2010 and gained mainstream adoption by 2013.

This halving mechanism mirrors the scarcity model of physical resource mining, according to Jameson Lopp, a Bitcoin security expert. The specific year 2140 simply reflects the math of halvings combined with the precision of satoshis.

Lopp highlights that Nakamoto explained the supply schedule to early contributor Mike Hearn in 2009. Nakamoto admitted his choice of coin number and distribution was an educated guess, aiming for prices similar to existing currencies.

While the total supply was set at 21 million, Nakamoto envisioned practical divisibility adjustments based on future value. For instance, if 0.001 BTC equaled one Euro, the system might display one Bitcoin as 1000 units, with 0.001 becoming one unit. (Interestingly, 0.001 BTC is currently worth around $70.)

The rationale for a 132-year decline in issuance remains unclear. Lopp suggests it might have been a "better safe than sorry" approach, giving the network ample time to establish itself.

As halvings occur, miner income from block rewards shrinks unless the Bitcoin price doubles every four years. To maintain network security (reflected by hashrate), transaction fees will likely become more crucial over time.

While the future remains uncertain, Lopp remains optimistic. He envisions a maturing Bitcoin ecosystem where the core blockchain acts as a high-value secure storage, making high transaction fees economically viable.