The contract relied on the key to mint new tokens. The hacker gained access to the key (through AWS) and with it minted as much as they'd like. It is certainly a valid take that a contract that only required the private key to mint an unlimited amount of the token isn't a good one, but you don't exploit someone's front door lock by grabbing the key from under the welcome mat.

While I am happy to celebrate dumb crypto stuff, this isn't a situation where someone's code was "exploited." Their code was stupid, relying only on an off-chain private key to allow the minting of tokens. Their security was just also bad.

Now, as to why the SEC hasn’t regulated crypto out of existence.. I refer you to dementia Don

It's not like I forgo a lock on my front door just because my windows are made of glass.

The main use is just having something dollar-like that you can move around easily. That’s useful outside the US, but also for plenty of people inside the US depending on what they’re doing; especially businesses that have a hard time getting or keeping normal banking (cough gambling, porn, weed cough).

They’re handy inside crypto since you can move in/out of other assets without touching a bank. And sometimes you can earn yield on them, which is part of the appeal (with the usual “this can blow up” caveats).

Also, there’s a reason every company wants to launch one: if you control the stablecoin, you get the float and the rails. That’s a pretty nice business if people actually use it.

If you already have solid access to USD and don’t care about that flexibility, they’re less compelling.

But yeah, not risk-free at all (depegs, issuer risk, etc). And honestly there probably isn’t much real need for dozens of slightly different stables beyond the business incentives.

But obviously...things happen. Just like cash is usually relatively non-volatile, but financial crashes happen.