Its just stochastic terrorism is the thing. Betting markets on a a negative outcome are ginning up a big "you could make money if the bad thing actually happens" and over enough scale you'll get that idea into the head of someone who concludes they should try and make it happen.

This is the same reason it is generally illegal to make public statements lamenting that someone hasn't killed a person.

https://en.wikipedia.org/wiki/Will_no_one_rid_me_of_this_tur...