Its USDT?
Lets say i have today 50$ so where i should keep it? Eur? Usd? Pounds? Gold? Usdt?
Bitcoin is not, maybe in future but right now bitcoin has too high volatility.
All currency you said are stable aside from bitcoin yes of couse bitcoin is highly volatility than the fiat currency is stable because we their orice are cintrol by the government unlike bitcoin is nothing can control it their price value are depends on the demands. But investing or holding bitcoin is the best way to get interest earning if their price goes uprise than to keep,a lot of fiat we know they can't get huge of interest keeping into bank.