what would you do if you would have let's say 100k USD or 500K USD with them?

I would ask myself why I was so stupid to have that kind of money in online wallet.
i dont think that anyone would be keeping that much money on an exchange that would be just dumb, i hope there wont be any of such hacks in the future
believe me, there MANY who are trading millions. one of them is a above, leen93. he kept aprox 1 mil USD with Bitfinex
now, these individuals lost their funds