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Luna's stablecoin (TerraUSD) was doomed from the begging. It was not backed by anything of value.
Unlike TerraUSD, $USDC is fully backed by US government bonds and deposits in american banks. The depeg happened because they held some of their money in the distressed Silicon Valley Bank and there was a risk that their money would be lost, later the bank was bailed out. Depeg due to bank failures or even US government debt default will always remain a risk.
Circle, the company behind USDC, is transparent and audited by Deloitte on a monthly basis. In contrast to Tether and their $USDT, which is rather opaque.
There are also other stablecoins like MakerDAO's DAI, backed by onchain cryptocurrency debt, Ethena's stablecoin backed by ETH hedged with perpetual futures and so on.
You should always #DYOR before investing as stablecoins are risky. Not everyone has access to the US banking system, but if you do it's definitely better to hold actual dollars than stablecoins.
US dollar is constantly losing its value, but not everyone is ready to be balls deep in crypto, so we need stablecoins for now.