Where I work we've had two major attacks, one was some punk kid that used a floppy disk on a workstation to do a DOS attack and the other was a guy I traced all the way back to Amsterdam who hacked one of our servers to share DVD rips. I took measures to stop him and watched the bastard try to get back in for months before he finally gave up.
Doing what I do and knowing what I know, no network is ever 100% safe. For instance I have this crap eating part time job and it's appalling how easy it would be for me to bring their network to its knees 50 different ways one of which I wouldn't even need to touch a keyboard! It comes down to a huge sense of personal responsibility and following the golden rule, I sure as heck wouldn't want someone doing that to me.
Unfortunately there are those out there who don't care, or they think its cool. In some groups it's a way to achieve status. This is a fact of life in this day and age and no amount of complaining about it is going to change that all you can do is take the best preventative measures you can.