Most of these "hacks" are inside jobs. They come up with excuses so they can easily run away with users' money. I've seen it time after time and it looks like this will never stop as long as there are greedy people in this world.
That's also my side like they even guarantee us a security yet how on earth it got hacked. Of course there's some sites that got really hacked but some of it is hacking itself scheme and just blame the action to hackers. So if you can avoid storing your coins to exchanges please do as those hard earned coins isn't a joke for us. Though if you really want to store then store what you can afford to lose.