Just to get an idea of how many people are using bitcoin.
We cannot count the number of people who have bitcoins since a person can have two or more wallets. There are no specific data also that tells that a certain person has bitcoin wallet since it is anonymous. If we are going to have statistics then we can say 1/4 of the people has knowledge in bitcoin and 50% of it are the one who have bitcoin. Therefore, bitcoin is not yet popular to the whole world.