Ones inability to understand how a crypto currency wallet works is on them. It's a pretty easy concept to wrap your head around if one was to look into it
Only a fool would keep their investments in any currency in someone elses hands solely without some form of "physical" copy. In the world of crypto currency, your money does have a physical form in the form of your "wallet", which you can store on the media of your choosing. BTC isn't legal tender, but there's still best practices involved. I've got 25 BTC left out of the 50 I mined years ago, safe and sound because I wasn't dumb enough to hand them over to Mtgox - and when I sold the first 25, I did sell them via Mtgox, in fact. The rest are on multiple forms of physical media in multiple secure locations. If you're foolish enough to keep your cash in the glovebox of your car and leave the doors unlocked, you get what you deserve.
Storing your investment solely somewhere like Mtgox where you have absolutely zero recourse for reimbursement should the brokerage go belly up is just silly, and the people that watched 750,000 bitcoins effectively vanish when Mtgox pulled the plug are surely kicking their ass right now, esp when a $5 USB stick would have prevented the issue had they not put undue faith in Mtgox
At $640 a pop atm per bitcoin, a lot of people right now are wishing they'd never heard of Mtgox, lol.