There are two different kinds of stablecoins. One is algorithmic stablecoins, which you probably remember from the Terra/Luna collapse. It relies on issuing/redeeming one cryptocurrency for another to keep the peg, which works mathematically unless the divisor goes to zero, which is what happened.

USDC is just a one-to-one stablecoin where for every coin issued there is one redeemable US dollar somewhere. People have accused Tether, which works on the same principle, of being a scam by not actually having a dollar for every USDT, but there's nothing inherently scammy or non-scammy about the system. It's like a bank, either they have the reserves they claim or they're committing fraud.