[grobbyy]

Yes, I could, but I'd have a 90% chance of hurting myself. Ditto for giving some cancer with radiation, many covert poisons, and similar. I can name a dozen ways I could kill or harm you, but:

1. I'd need to be wacko enough to want to harm you

2. I'd need to be sane enough for a major engineering project

3. I'd need to be competent enough to succeed without hurting myself

The set of individuals with all the traits required is small. It's not zero -- we had Ted Kazinsky -- but very small. Most major crimes are also never solved, and many more people can just take a gun and shoot someone. That's probably even harder to track down since a lot more people have guns than labs and PhDs. Esoteric technologies make for easy investigations.

So in the end, I think state actors have these. They also make good plot lines for a novel or video game (I have about a dozen I came up with in the context of a half-baked creative project).

But for real life individuals, I don't see how they'd become prolific. We'll probably see a crazy someday, but nowhere close to gun homicides. They just don't make much practical sense for an individual.