If Bitcoin is treated as a legal currency, or the function of completely replacing legal currency may not work. After all, the total amount of Bitcoin is limited. As the amount of Bitcoin mining decreases and gradually approaches the total amount, people may be reluctant to sell themselves. Bitcoin in hand, it reduces circulation and becomes deflation, and we also know that Bitcoin has a relatively high daily volatility, and there are problems such as transfer fees. There may be technologies such as the Lightning Network that will slowly solve these problems. But I think Bitcoin is still not suitable to be used as an actual currency.