I think the reality also is that there just isn't many people who want to do stuff like this. Like the reality is that a guy with 200 in cash could put together a shitty walmart drone with a pipe bomb attached and terrorize more or less any event he wanted. Maybe a llm that could talk you through every step involved would make it more common but it's easy enough I kinda doubt that

This is the right answer. There's a ton of easy low hanging fruit ways to do absolutely horrible evil things with high potential body counts. I could sit here and brainstorm dozens.