https://www.youtube.com/watch?v=g5iCx8cY6l4&feature=youtu.be
Though this is alerting but don’t forget that most of the cases involve are human errors means we are the one who is responsible for each hacking because we don’t use precautionary measure and by lack of knowledge about how properly used the internet,phishing sites and malware issues are the common reason ,if we want to prevent this then make your bitcoins more secure an safety
So once again, we need to be careful to save the coins in the exchange or another wallet because we are the owner and we need to give attention about this if we don't want to lose the coins. And if we can secure every wallet or account in the exchange, we do not have to worry from the hacker unless the exchange has a problem with their security. So far, we might see that it's happening in many exchanges and maybe they do not always check their security and searching for a hole or bug so the hacker can penetrate to the database.