They can stole the invests and can say that hackers has stoled the invests and anybody can not say not 'it was you'. Like Mt, Gox.
with mt gox, there's
some pretty strong evidence that alexander vinnik and btc-e were involved in the theft.
Please stop exemplify about Binance. It was their initiative and good for them. But not every exchange like them.
coinbase has an insurance policy that covers its online storage. like binance, they can cover a hack like the one that occurred in may. as for other exchanges, you're right.
So how can you trade securely? Do you feel comfortable?
don't store funds on exchanges. use them to trade and then withdraw immediately -- minimize the time you're exposed to third party risk. do some due diligence on an exchange before using it. you could also consider trading p2p instead.