I have a simpler answer to this, Satoshi Nakamoto is fascinated by the number 21 

ladyluck

This and other theories - https://thenextweb.com/news/heres-why-satoshi-nakamoto-set-bitcoin-supply-limit-to-21-million

dcc636d03c

I recommend this podcast, where Saifedean Ammous and Pierre Richard talk about this subject:

https://fountain.fm/episode/rFQ9MS8KGOpFYCAVWXgZ

BitByBit21

bitcoin_beginners

# Why is Bitcoin capped at 21M, and not some other number?

Probably this 👇, but I'm not sure at all.

Number of blocks per four years cycle (_assuming perfect timing of 10min per block_):

- 6 blocks per hour
- 24 hours per day
- 365 days per year
- 4 years per cycle

`6 * 24 * 365 * 4 = 210,240 ~= 210,000`

Sum all the block reward sizes:

`50 + 25 + 12.5 + 6.25 + 3.125 + … = 100`

Multiply the two:

`210,000 * 100 = 21 million.`

Which is summarized by the formula:

![subsidy_equation.jpg](https://m.stacker.news/11192)