i get that some people want to keep money on a exchange in maybe USD OR EURO so they can buy whatever coin they want fast [...]
There is no need to use an exchange. Many of them have ridiculously high fees (mostly withdrawals) and force their users to pass through KYC verification. I would rather use
Changelly or some other third party service which offers quick exchange between different cryptocurrencies. Even TREZOR started supporting these kind of services natively in their web wallet interface.
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.