Insurance for cryptocurrency exchanges is a good idea if this is not already done.
It was discussed before. Insurers need quite a lot of knowledge about blockchain and they may not too eager to learn. Also if the number of insurers is small (and at start it's clearly small) they may ask too big fees.
Crypto volatility is again a problem. If one insures 100M and the cryptos double the value in less than one month then gets hacked, still half of the hot wallet is lost...
At any rate, Binance made the right decision of establishing a fund specifically for emergency situations
Yep, it was the decision that helped them not fall into oblivion.