You don't. Hacks target the exchanges wallet by finding exploits and not the user accounts separately. If you want your funds to be safe, use exchanges for trading only and withdraw to your personal wallet.
it makes me little scare sir, how about the wallet? it's still safe?, if you have any recomend ,what's good exchanges sir?
There is nothing like a good exchange. If you are holding for the long term, you can decide to go the cold storage way. If you do not have the cash for stuffs like ledger Nano, you can just generate a paper wallet and your public key is the only thing you need to always receive funds.
As long as you are not trading, never leave your funds in an exchange and even if you are trading, make sure your account security is sound enough.
One thing is to always make sure safety is paramount when it comes to cryptocurrency just like the OP stated. We cannot always avoid some of these things, but the earlier people started knowing how to stay secured, the better. Expert hackers or not, if you leave yourself vulnerable to an attack, you will definitely be a victim and the best is to always be on the lookout, most especially for any phishing links.
Exactly, if you only use bitcoin occasionally and you are not an investor then losing a few dollars is not that important to you but if you have invested in bitcoin and you want to take care of that then you need to take step, people need to remember we are our own banks which means we are responsible for our own security and if we fail no one is going to assist us to recover our money.