I’m not going to dig through all of them (especially since that number includes gang violence, which is a lifestyle choice, and falls outside the scope of what most rational people would call “mass casualty events” or “active shooters” etc,) but yeah th Nashville shooter had one, the grocery store shooter had one (buffalo iirc,) columbine, parkland iirc, the list goes on. They plan them for a long time. Same with McVeigh, Kaczynski, the Nashville bombing guy, the guy who shot up the republican baseball game, these people don’t typically “just snap,” it has been brewing for months and they’ve been planning.

The “just snapping” thing has historically been associated with family annhialators (as rare as they are) if any mass killers, usually just “single murderers” who kill the spouse, but even then if no gun is present they’ll “just snap” and kill their family in another way a la Chris Benoit. Guns don’t have to “make it easier” when you can drug people you’re more physically fit than anyway, tie em up, choke them with cords. If my ex wanted to kill me for instance all she’d have had to do is stab me in my sleep, seeing as we slept in the same room and all.