stablecoins are really useful in this market that is always volatile, you can keep your assets safe at stablecoins, useful in buying and selling very large because their value is not lost, and traders need stablecoin.
The stable coin can be a very good option for those who wanna try to avoid the volatility, stable coin can also be used as a stable payment system too that the merchant will not feel worry about the possibility to get a loses due to the volatility.
But why wouldn't those people choose fiat money that are as stable as stablecoins but also backed by the government?
Most stablecoins are backed by promises and some are even backed by lies (usdt).
My opinion is that stablecoins can be useful by people who are not allowed to trade coins for fiat money or want to avoid taxation by exchanging to another coin instaed of fiat money but that's it. Don't ever trust stablecoin or treat them like an investment.