This feels a little bit like trying to read tea leaves or something, but what the heck. Here's my interpretation:

The shooter by some measure led a successful life. But something wasn't right. Some bitterness, some poison in the well of their soul. They were really rejecting the rest of a life that seemed destined not to improve in whatever material or spiritual way it felt broken. They committed to something atrocious, perhaps an expression of how they felt about their world.

Maybe events like these are like mineshaft canaries that attack instead of just die. They're an indicator that our society collectively is failing itself in substantial ways. I imagine that most people who want to see progress in the world feel a similar sense of malaise, they're just more optimistic, moral, or willfully benevolent-minded. That can be a matter of culture, and it seems lately we've been gestating sociopathic and divisive culture instead for petty and depraved political establishment's purpose.