If you divide 21 million by 8.036 billion people, that leaves only 0.00261324 Bitcoin per person.

Reduce that number further to account for all the sats that have been permanently lost due to lost private keys.

Reduce that number further to account for the fact that most current Bitcoiners already hold more than that.

Even with 2.1 quadrillion sats, there really isn't enough to go around.