It sounds like he was hoping for an out with a suffocating family and fantasised it being easy for him.. but then it wasn't. I don't know what his home life was like, but in many abusive homes, the kids won't think past the solution.. the consequences. All that matters is ending the suffering they are going through and whether he was abused or not, he felt like he was suffering. Who knows. Not that I justify what he did.
And no, this isn't a new thing. Humans kill. Most of us don't, but it's in us to kill. We are animals in the end. And a look throughout history will show you we are nowhere near as violent and mad as we once were. But everyone still goes on and on about "kids today" like they have throughout history lol. I don't know if he's mad or just lost and made the worst decision of his life.. but what's done is done and he needs to pay for it.