21 Million Bitcoin is 2,100,000,000,000,000 and current world population is 8,100,000,000, it's mean each person can own 259,259 Satoshi in order to be distributed to every people. Can someone who have a faucet account and claim 1 Satoshi can be said as owning Bitcoin? although it's not actually you have that Bitcoin because there's a minimum amount to withdraw and other thing.
Theoretically everyone in the world can have Bitcoin.
Wow, how can you be so sure that the world population is 8.1Billion? This is not accurate, the numbers of humans living on this earth is more than that, and no machine is capable of recording the exact number, there are loads of people that are living in the areas where there is no screening or counting for us to actually know their numbers, some are tribes that are not counted as part of the people living in the cities, because they are always in the jungle or the Amazon forest.
Every single person can't own Bitcoin, some will never be able to afford to buy It and some won't give a damn, even if it goes up to one million dollars they won't still care.
How many people are owning Gold today? I have never invested in Gold before and I don't care about having some Gold locked up in my basement because I don't see any reason why, it's not as if I will die because I don't have some Gold, it's the same with Bitcoin, it's not a do or die.