Coins should always be considered in a safe storage, there are lot of wallets and platform that could be used to hold coins, both of this has good side and bad. Where will you choose to store or hold your coins, in a close source wallet (exchanges) or an open source wallet?
Firstly, I guess it can be close or open wallet depend to the investors. They have their own reference for saving their coins. For me, in a close source wallet (exchange) I can save mine more safety. IT gives us control and privasi in doing or processing anything.
I'm not sure about saving or holding in an exchange, most of people here suggest to keep it in a secure wallet like hardware or opensource wallet. Currently, I'm in with Hodler wallet which supports all preferred coins, it is the only fully opensource multiwallet available which assures me that that I have the control over my funds.