I do not recommend to save a lot of money on an exchange only, otherwise I do not recommend you to trust only on an exchange only. This is very risky because as we know that many exchanges are experiencing problems, there are some who experience hacking and it makes all funds owned by the user is lost. That's why I say that exchanges are a risky way of storing large amounts of money. So for me the wallet that has a private key is a good choice, in addition to safe we will also get a sense of comfort because we will not worry in storing funds in large quantities and in the long term.