Tether has always had issues with reserves to guarantee value for USDT, so USDC becomes a better stable coin thanks to the support of Circle and Coinbase. I also transfer part of my USDT to USDC for more peace of mind in this market.
Well, when USDT has not had that reserve guarantee problem, since always, and in fact any other stable coin, this 'tokens' are like a bridge, you use it on the way correct, in the metaphor of the bridge they are that, a period of time, I do not understand the widespread concept that believing that you diversify between stable coins is peace of mind, well at least in a partial part of your assets but not total, I hope that is your case, otherwise I do not see what your peace of mind is.