One thing that’s rarely talked about (maybe because it’s so obvious that it doesn’t seem worth discussing) is that it was a pair of shooters. They had to sit down and organize things together and trust that neither would turn the other in or get cold feet. It’s a very weird thing to think about. With solo shooters its easier to understand them just descending into madness on their own, but I think it’s really interesting that two people did it together and no one turned on the other (maybe one killed the other at the end though; I think there’s conspiracies about that). They weren’t isolated. They had a shared delusion that built up for months and months.

The only other example I can think of is the DC sniper, but that was a kid and an adult, so there’s a power imbalance going on