I think we all have money in exchange. And not only 1-2, but dozens of exchanges. Because each ICO is negotiating with another platform after a certain period of time. Therefore, it is useful to be very careful. I think we should use our own personal wallet as much as possible.
Everyone who trade, invest and to make profit does have money in exchange. You're defining the IEOs here which would really require the platform itself and as much as possible you should stop investing with any of them, ICO or IEO.
And as for your wallet, you should hold the keys no matter what. Don't entrust large fund to any exchange whether they are reputable and running as long as you don't hold your private keys, your money isn't in your hands.