You are guaranteed $100,000 in free insurance when you deposit your money at an FDIC-insured bank.
No matter what bugs, attacks, malware or whatever happens, the US Government will pay you back your deposited money, to the fullest extent that it can.
If you don't see why this is useful, maybe you need a sanity check.
The only way it won't pay you back the full 100,000 is if the US goes bankrupt. Which considering the US dollar is the world's reserve currency, is not going to happen.
It's $250,000 now (since 2008). Also it's not technically free. Insured banks pay premiums to the FDIC to cover the costs of deposit insurance.
But I agree 100% that the idea that a cash account at a random bitcoin exchange is somehow as reliable as an FDIC insured bank is a completely batshit crazy notion.