The veteran people on crypto tend to say that you should keep your coins in your wallet, never on exchages. However if there is a strong downwards movement on a coin and you want to sell to buy latter at a cheaper price it may take quite a bit of time and fees to move it. What is the right strategy?
They think so, because in 2016-2017 many exchange was hacked.
But
If you want hold - you don't need exchange. Hold on exchange is bad thing.
If you want trade in short term, you want legit exchange. And now is a lot of great exchange's.