Stable coins are stablecoins, there is really no going up or down for them, whatever they make they are just printed out of thin air without really no backing and people buy them so they end up being basically used that way. Obviously there is a HUGE problem with it about the companies behind them, one day they could say that they are not going to give any fiat in return and you would be left hanging with some stablecoins that worth basically zero, which is the only trouble you could face with them.
This is really possible as stable coin are handled by the developers and once they've declared something there's no chance for
you to recover, you should deal with more study before taking your next move holding this asset.
There has been a lot of companies who tried to mimic what USDT is doing and a lot of them failed since people didn't used it that much and they weren't listed in every exchange like USDT is listed. So all in all the best way to actually invest into stable coin is a little amount that you are not afraid to lose.
You can use it a alternative but make sure to keep in mind that there are always a risk same with any other investment around, the
more you know what your are doing the lesser the chance that you'll lose your money.