What can be done to stay safe?
Don't trust the exchanges. They have been hacked before, and will be hacked in the future.
Exchanges are a huge attack vector. As they have to keep a huge volume of coins online, many people will be trying to hack it.
There is also one more problem related to exchanges.
Even if the exchange is not hacked, governments can force exchanges to freeze your account, or take away your money from you.
The exchange controls the private keys, and governments are regulating exchanges everywhere. They want taxes, they are creating bureaucratic rules, etc, and exchanges must follow all those rules to keep running. If governments or the exchange see any problem with your account and the money you have stored there, they have the control over it.