This is obviously in response to a recent event, but unfortunately, what I'm going to say is pretty timeless, so I won't bother linking to the specific stories that inspired this post, since it's almost certainly going to apply equally well to whatever recent mass murder has captivated the public eye at the time a reader finds this.
I have something of a history of empathizing with the manifestos of spree killers more than most folks are willing to admit. I look at their arguments and say, "that all sounds reasonable up until the point of the random mass murder". Over and over again. Makes a person a bit paranoid when no one else around you seems to think there's anything but crazy and evil in there.
I have never gone on a killing spree. I have fantasized about doing so. I've been tempted numerous times. The world isn't a just place, and it's easy to just say "fuck it, let's burn the whole thing to the ground" rather than commit to the impossible Sisyphean task of fixing everything that's wrong with the world.
I'm the sort of person who thinks the world ought to be reasonable, equitable, and just. That belief crops up in almost every one of these spree killer manifestos that I see. They look at the world, see that it isn't fair, and can't deal with that fact. This isn't about entitlement, at least as far as their writings go. They don't just think the world's unfair TO THEM, though that's usually what made it impossible to miss that the world was unfair. They think the world's unfair to whole categories of people, and once those proverbial scales have been ripped from your eyes, it's a long journey of seeing all the ways the world is unfair and unreasonable.
I was in elementary school when I got my first taste of this. I noticed age based discrimination. It was compulsory education I noticed first. The problem, as I saw it, was not that I was being forced to attend school. It was that people who lacked the knowledge base that I was supposed to be aquiring in school were not being likewise forced to attend simply because they had passed an arbitrary age line. I considered violent revolution as a potential solution to this problem, since history classes had made it clear that was how you accomplished change on that scale. I lacked both the martial skills and the personal charisma to organize such a revolution while in elementary school, so that plan didn't get anywhere.
The problem I was looking at wasn't just childishy whining that I was being forced to go to school. It was recognizing that an entire category of people, of whom I then happened to be a member, were being systematically discriminated against, and deciding that something needed to be done. I was repeatedly told I'd change my mind as I got older, but the fact of the matter is, I'm still that young boy who saw a problem, and occasionally toys with the idea of violent revolution in order to fix it.
The reason I never went on a shooting rampage is that I came to the conclusion it wouldn't be effective. I've seen so many of these spree killers over the years, and each time it's the same thing. People handwring over "what could have brought this on" and then people utterly ignore the efforts those killers made to explain exactly that, instead preferring to cynically exploit the killing spree as a means of advancing their own pet issues.
I'm still looking for a way to fix the obvious injustices in the world. I've eliminated random mass murder as a likely avenue. Irrationally, I hold out hope that one of these days I'll find a tool that will work.