> what you are saying is we can expect the number of accidental home-made chlorine-gas (and the like) toxic events go up

Maybe? One of the quirks of gaining even a surface-level understanding of infrastructure is realising how vulnerable it is to a smart, motivated adversary. The main thing protecting us isn't hard security. It's most Americans having better shit to do than running a truck of fertiliser and oxidiser into a pylon.

Similarly, I'd expect way more people to be trying to make their own designer drug, and hurting themselves that way, than trying to make neurotoxins.