Don't go by the numbers. Less than 5% of Indian population have ever heard about cryptocurrency and those living in the smaller cities and rural areas are completely unaware of it. There are less than 10 million users in local cryptocurrency exchanges. If you add the P2P users as well, then the figure may come to 20-25 million. But still there is a good chance that there are more users in Nigeria (at least in terms of number of active users).