Source of the quote.
At this point in time, after many years and countless scams we have determined the following about the exchanges (all or almost all of them):
- Exchanges are not your friends. They are here to profit off you. They don't care about you in the least
- Since gambling with your money apparently gives a lot more profit than just collecting trading fees, exchanges prefer to just do that.
- In fact, traditional banks have been doing the same for centuries, for which reason this white-gloved crime has been legalised as a thing called "fractional reserve"
- Exchanges have been caught trading against their customers. Multiple times. So if you think you are clever and you can play against the other players, remember that house always wins.
- When the above do not give enough profit in sufficiently short time, many exchanges also choose to run off with your money (via scam, hack or bankrupcy) instead of running a semi-honest business
Bitcoin (and cryptocurrencies in general) have been designed precisely to combat all of the above, so think what you are doing when holding crypto on exchange. You're not actually using cryptocurrency, you're using a new banking system.
Again as always, the basic rule is not your keys, not your coins.
If you don't have the keys to your crypto, you do not have any crypto. Cannot repeat this enough.