Well, I think that loading Bitcoins to an exchange is similar to opening a deposit at your bank. There is no 100% guarantee, but you still have criteria to choose the best and trustworthy exchange or bank. If you don't want to do that, keep your money/Bitcoins under your bed/in your wallets.
I mostly keep BTC on my wallet, and trade the rest of them on CEX.IO. I chose them, because they've been on the market for a long time, have registration docs right on the website, PCI DSS certificate, have cold wallets, and all the stuff. And they suit me in terms of easy deposits and withdrawals using credit cards, which is very important for me.
Slight difference... most banks (at least in the place where I stay) have insured deposits (to a certain extent). They are also regulated and so you know for sure that certain safeguards are in place.
With bitcoin exchanges, you are in the wild, wild west.