It is so funny that some people are thinking bitcoin can replace fiat, if they only know the total number of users of bitcoin then they will realize it is not possible, not even in the future. Currently, the users of bitcoin is not even 1% of the total population of the world.
If you say bitcoin users no more than 1% of the world population was wrong. I think bitcoin users now have grown dam may be around 12%. It is still a small number, but I'm sure to increase. But you really can not replace the bitcoin money, because money is needed by many people to deal directly. Although later bitcoin used as payment but the money still will be needed.
you're both wrong because your statement is unreasonable and can't be proven either,the amount of bitcoin users until now still can't be calculated as there's still no way to get the number because a person could possibly holding so many wallet,and the money can be replaced when the world will be digitalize and forcing people to use digital money in order to reduce logging in this planet