Personally, I am a small-time trader and I am storing my cryptos in some exchanges. Yes all exchanges are risky, just like the way all cryptos are risky as well, Do not store all your cryptos on one exchange only, that's the real risk, but store them into some different exchanges as a precaution.
That is still risky to be honest. The fact that you are storing your cryptos to an exchange that has a high possibility of getting hacked or going to a maintenance, you might lose your cryptos or you will wait for period of time before getting it. Why not store it in a safe wallet like ledger nano or MEW if you can't afford a ledger nano. It's not like the fee for transferring your cryptos to an exchange is that expensive right ?