It's hard to make a profit from stable coins, even if they can, their profit is not bigger than the other coins. The stable coin can works for you if you sell your bitcoin or altcoin, and hold it until the bitcoin or altcoin is down so deep so you can buy back again that bitcoin or altcoin. But if you are okay with the risk, then you should try to trade and make a profit. The lose will always be on the trader, whether they want or not, and that will depend on how good are you to manage the risk.
I apologize, but maybe I didn’t understand the essence of your dialogue a bit, but in fact I also use USDT in trading pairs to trade certain cryptocurrencies. For scalping in my case it is very profitable. I choose a specific cryptocurrency, for example, ADA, LEO or LINK, and buy this coin or sell it using USDT. Of course, I do not have much experience in trading, but I minimize my risks by using the USDT trading pair with other cryptocurrencies.
Good if you can make a profit from altcoin pair USDT. People who trade with altcoin pair bitcoin is not trying to trade altcoin pair USDT because many of altcoin is not traded in the USDT list. Besides that, they think that the profit will not bigger if they still hold in the bitcoin or altcoin forms, and not USDT forms.
So they still traded as usual, and hold the altcoin or bitcoin forms, not in USDT. The longer they hold the altcoin or bitcoin, there will be an increase or decrease for the coin, and that can make them stress. But if they convert it into USDT, they will not see the decrease of the value because the USDT is not down too far.