Since dollar is centralized, it means the government and regulators can seize your money at anytime or change the present economic policy of your country, besides it being under heavy devaluation due to inflation. On the other hand, if you have Bitcoins stored under your custody, nobody can take it from you, neither governments. Bitcoin is decentralized, therefore it can't disappear, because there aren't central parties with such powers. Decentralization is in fact the guarantee Bitcoin won't disappear and won't be seized from holders.

What can happen to BTC is to lose value in case demand diminishes, but that is really unlikely to happen for now, as we are seeing the market getting more optimistic towards cryptocurrencies for the year of 2024 onwards.