Your question actually I think multiperception. Depending on which point of view someone will catch your question.
If the meaning of your question is only related to "numbers/mathematics/amounts" and apart from other factors that affect the adoption of Bitcoin then of course the answer is that it is possible for everyone to have Bitcoin even if the supply is limited or even a little, because I think that "number/mathematics/amounts" is definite things and every number regardless of the amount of course can still be divided.
But if you have linked it to the factors that influence Bitcoin adoption, then the answer is of course that not everyone can have Bitcoin because of various internal and external factors for each individual.
Internal factors I mean such as individuals' desires, interests, beliefs and knowledge of Bitcoin. While external factors I mean such as financial conditions, technological advances and the internet and government regulations regarding Bitcoin in their respective countries.