RE: When you send crypto to an Exchange it's no longer yours untill you get it out again.

[cryptodan]

You are absolutely right and this needs to be top priority for people who trade in the exchanges.
I see a problem though in the lack of multi-sig wallets who can hold multiple and especially more obscure altcoins. Because of this people have to acquire multiple wallets in order to store their crypto, and I'm guessing many people don't want the hassle of having more than one wallet which is why some just leave their money on the exchanges, sadly...