USDT and USDC are even worse to buy and hold because they are something else; they could easily be depegged under any circumstance if the issuance company has the possibility of its value returning to zero, and then again, instead of holding USDT, I will better advise the person to hold a physical USD and save it up on their personal volt; it's safer since there are no differences since it's still the same fiat.
Physical USD is ordinary money which is also often used by many people to buy and exchange it for the goods they want, meaning that in terms of the level of profit there is nothing except the stability of its value in life. Meanwhile, USDT and USDC are tokens or coins that exist in the crypto market to make it easier for their users when they want to buy or exchange them for other coins because both of them still have more pairs in the crypto market. And in terms of keeping it for yourself, I don't think it would be a problem if it was only for a while before everyone exchanged it back to Bitcoin or something else via the market.