You're doing the opposite of what is actually safe. Of course there are ways for hackers to get data from your computer as well but if you have significant amount of coins, you should implement some safety measures and you'll be good. Use hardware wallets, backup things that need to be backed up, set good passwords, don't use open wi-fi networks... If your coins are on exchanges you have no control over that and even the largest world exchanges used to get hacked/fail in some other way. Sure that exchanges are getting safer but hackers are also learning things, and there is always that human factor that can compromise things in any system...