In my view there's two issues here:
Firstly, remember that the technology, whether it's a plane, a computer, a gun, a car, etc, is neutral. It's up to us and our community to foster responsible applications of that technology through appropriate education, training and licensing.
In my job as a college electronic and computer systems engineering lecturer this is always on my mind. The students passing through my classes, and those of my colleagues, are exposed to and trained in the use of some fairly powerful technology. However, despite our best efforts, in 15+ years and a few thousand students, there have about 10 or so that I know of that have applied what we have taught them to criminal activities; phone phreaking, internet account hacking, software piracy, etc, in each case they've been been fined and imprisoned. And in each case we all wonder what we, as the educators and trainers, did wrong? But then we think of the many hundreds of former students that are applying their craft honestly and responsibly; installing and maintaining medical systems in hospitals, in telecommunications, in aviation, in manufacturing and processing, in surface transport control systems, and so on. As responsible citizens they are making our world a better place to live in.
The second issue is this virtual world that you are inhabiting when you are reading this post. Most of us to varying degrees can mostly accept what we are. Ok we all have regrets from time to time, you know "if only ... ", and may not be always totally happy with ourselves and or our situation, but we get over it to a fair degree. We make the best of what we have, make the effort to achieve new goals if we want to change ourselves, and are generally reasonably honest on forums such as this. Unfortunately, there are a few who can't distinguish between this virtual electronic world and so any fantasies developed here, instead of remaining an imaginative game, spill over into the real "real" world where real people can get hurt. I would say that the sociological jury will be out a long time on this issue.
There is nothing no one on this forum could have done to directly prevent this particular tragic event but in the future please all look after yourselves and your friends - go for a long walk in the real world, kick a football in the park, shoot some hoops, smile at people, and generally get a life I guess.
Take care and no guilt trips ok