Of course, the hackers say that there is no safe place in cyberspace but that will happen if you do not make mistakes in keeping your key because all security provided in myetherwallet is useless if the users themselves are not careful. hackers usually use phishing sites to get information about your account and your security key so you should be able to distinguish this site, if you click on a phishing site then you do not realize that you have submitted your account information.
Phishing attacks are the number 1 reason of people losing their coins in myetherwallet, people need to access that site only from a bookmark of the legit site, never access that website following a link, you could be redirected to a different website that looks the same or you could be infected by malware, but people do not listen until they lose their coins.