Oh, they exist so they can throw their peg and crash losing 99 percent of their value while the company or individuals responsible tell their users not to worry and that it is totally under control.
for a company like this, the real reason is because you can give users 0% return while on the backend actually making return with their money, same as any "bank" that holds usd.
for people like do kwon and sbf, and many others I probably don't know about, what you said
Banks are competing for deposits; this rate pressure is already hitting earnings. And they take maturity-transformation risk. PayPal has found ersatz depositors without depositor protections who will accept zero yield in a high-yield environment. They could literally just roll into Treasury bills and overnight funding and ink a decent profit.
for people like do kwon and sbf, and many others I probably don't know about, what you said