In my opinion, the number of bitcoins that are only 21 million is classified as not much for the size of the currency that is spread throughout the world. Bitcoin is classified as an international currency even though it has not officially obtained legality in all countries. But this limited amount is indeed one of the obstacles for bitcoin to be able to balance its supply and demand. If the number of bitcoins is increasing and there are more players, the stability of bitcoin will last longer and the future of bitcoin is also more guaranteed.