Even an audited exchange like Coinbase that is trying to do everything right is still self reporting loses like $430M in quarter 1 of 2022 just by operating their business correctly. Not your keys, not your crypto. Anyone storing their crypto on any exchange has this risk.
How do you lose so much money when your business it to charge fees? You'd have to do something really stupid to not make money.
On top of that KYC and other operational costs really add up, and without another revenue stream than the transactions themselves it may simply not be enough of a slice to be viable.