You won't find very many people that have been doing this for very long that think keeping more than necessary on an exchange is a good idea.
If you think it is, you just haven't been doing this long enough. Learn to manage your own security and wallets.
Correct.
Over the last 5 years nearly every exchange gets hacked...its a matter of when not if. Its been a while since that last big one so probably we are due one soon that will remind people. With an exchange you are basically handing your coins over to a stranger on the internet.
Only coins kept on an exchange should be ones you can laugh off if you lose.