Bitcoin in 20 years will be too expensive to purchase a full bitcoin. At that time, the government will in one way of the other grant the use in the daily activities or will be used as an internet money for international transactions. At that time, it will be an investment asset to all new users and even people not in the crypto world, where all other altcoins will be used for crypto trading, and maybe ETH will come to be the number one as BTC will be out of reach.