What Is the Mechanism That Prevents the Bitcoin Block Reward from Halving Indefinitely?
The block reward is subject to a halving every 210,000 blocks until it reaches a value of less than one satoshi (the smallest unit of Bitcoin). The reward will eventually round down to zero.
The final halving is expected to occur around the year 2140, at which point the block reward will effectively become zero, and miners will rely entirely on transaction fees.
