This problem exists with cash. We teach people to not keep too much cash on them, but to keep it in a bank where it is safer.

You could get a credit card, and then it’s not even your money that you are spending! or your money that you lost to fraud.

I can see both of these existing in the crypto world in some form, the same way they exist in the fiat world

as for the banks and institutions and companies losing all of their money? that’s a new blockchain problem for sure