None exchanges are safe.
People have their exchange accounts stolen all the time. As you can be hacked from anything on Internet. When a hacker gets the access to your browser data, you are done. You accounts will be stolen along with your exchanges accounts.
Dont store coins on exchange. Withdraw them asap when you have them.
only the trust of users is the strongest factor for them, I use the exchange market for quick profits and in the end I will send it back to Mew or blockchain. there is no market that really has a full refund guarantee, they also panic when they lose their own assets, this is very disappointing because I see the thefts that occur are similar to their own conspiracies.