what if there is a successful hack attempt on Binance and they lose a major portion of their cryptos

Then that means their security is lacking. I recall some hacks are successful though. Albeit it only affects their hot wallet. I assume a lawsuit might come against them even if they claim they were hacked. I believe the market will eventually recover even if one or two big exchanges collapse.
Personally, other than the decrease of Bitcoin and other crypto, I doubt Binance being bankrupt will affect me in any way. I no longer use them since months/years ago and my local exchange is clearly better for my needs. What worries me is if they are trying to acquire more local exchanges. Hopefully, that doesn't happen.