Isn't the collapse of FTX in some ways evidence in favor of decentralized currency rather than against it? As evidenced by 2008, firms gambling with other people's money doesn't seem to be specific to DeFi.
If coin exchanges had some legal obligation to just be wallet and marketplace services instead of investment engines, could that help prevent this sort of fiasco (and the 2008 one) happening in the future? On the other hand, perhaps this solution could be equally applicable to traditional banks.