From what I gather, a "bitcoin" was an arbitrary decision to fix the decimal at 8 digits. 21 million Bitcoin * 100 million sats per = 2.1 quadrillion. Right now if distributed equally, that is about 240,000 sats per living human.

As Bitcoin gains value, sats will eventually become the denomination. Already today ~3300 sats is equal to a dollar. Another 10x, and a sat is on the same order of magnitude as a penny. We are close already, I find converting Bitcoin and fiat prices easier in my head with sats, vs with a full Bitcoin