The fee part is incorrect. Coinbase offers 1:1 exchanges of USD<>USDC with zero fee.
On FTX it's the same, USDC and USD are treated 1:1 with no fee to convert. Deposit dollars, withdraw USDC or vice versa.
Aside from these zero fee exchanges, many others have significantly lower fees for stablecoin<>fiat than they do for crypto<>fiat.
Because I don't possess any USDC and acquiring some requires me to open an account with Coinbase or FTX or whatever, send them dollars, and then purchase USDC. And even though sending the USDC has a low fee, the exchange fee for purchasing USDC is nontrivial (1% at Coinbase).