i think you forget that people also use exchanges for trading, as a mean of income.I myself do lot's of trading, but i try to keep as little coins as possible in the exchange whenever i'm done.
Well, I didn't forget about such people. Changelly, for example, supports Tether which is also used by every single popular exchange. You might find it less convenient but it's definitely more secure especially if you trade occasionally. I am glad to hear that you have good habits but don't forget that there are many people out there unaware of potential risk. People haven't learned much after Mt. Gox incident from a few years ago.