Many people write that USDT is not stable, I personally have been using this coin for a long time and I am fully satisfied with it, it has proved its safety over time
Yeah, it's absolutely true. USDT is the most stable of all stable coins. There are various statistics on this and the standards of the USDT have been proven.
I haven't used any stable cryptocurrency other than USDT until now, but I can say I'm pretty confident.