I think there are 2-3 things that make this happen. One of them will be the most essential point, but first the technology and the possibility of a human being. In africa, people will not have the same opportunities as people in europe or america. There is no internet, or they dont have a computer with which they could buy bitcoin. This does not mean all people in africa. When tehre about 50% of the people in Africa dont have a bankaccount, that should be about 600 million people.

Secondly, many people do not have mutch money to invest, with a chance of losing everything. Many dont risk something.And last but not least: Understand what bitcoin really is, only a few.