The buyer is wise, and that is why he/she prefers to transact using stable coin and not bitcoin as bitcoin is more valuable than every other crypto asset combined. I definitely will save my bitcoin too.
It might also be that it is due to price fluctuation, some people fear when they see their money becomes less and when they see that it will become a problem in the future, they will prefer to have their payment in USDT instead. The bitcoin also have low demand if you try to sell them on exchanges, I have experience this problem in P2P when I wanted to sell Bitcoin, the rate were low and I have to convert from Bitcoin to USDT and as soon as I did the conversion, the rate which I sold were very Okay and reasonable when you compare it to the rate of bitcoin.