Fewer than 21 million bitcoin will ever exist, and there are more than 8 billion people. Divide one by the other and each person's equal share is a few hundred thousand sats, a fraction of one bitcoin. Take out the coins that are probably lost forever and the share shrinks again.
This is not a target or a suggestion of what anyone should own. It is a way to feel the size of a fixed supply. Try your own country's or city's population, or type an amount in sats to see how many equal shares it is.
Related lessons: 21 million and no more, Lost coins and the real supply, The supply schedule.