I think there is no limit to hold stable coins, and you can hold as much as you want. And if you have much usdt in your wallet, I think you can buy bitcoin and other potential coins at a low price, so you will have a chance to make a profit in the future. If you only hold usdt, you will not see the opportunity for profit because usdt price is not up and down too far, and only bitcoin and altcoin will have that chance. But that will be up to you, and if you choose to hold bitcoin or altcoin, you need to know the risk.