Earlier quoted context omitted.
There used to be a thing called "Moore's Law of Mad Science": "Every eighteen months, the minimum IQ necessary to destroy the world drops by one point." Nowadays it is dropping much faster. At a certain point, the de-facto IQ needed to destroy the world will be low enough that someone can do it while they're having a psychotic break. There are millions of schizophrenics worldwide. Are you sure you want to roll those…
That law is not based on thorough data. Even a person with a sky high IQ can't destroy the world easily. You need access to stuff that is not easy to get. My guess is that developing a new lethal virus or bacteria that is very infectious, is the easiest way, but even that requires a lot of high tech out of reach of most people. Or hacking into systems that control nuclear missiles, but I think these have "air gaps".
You can do at home gene editing with open source software and have it synthesized into a bacteria for the cost of a nice meal for two (under $100), or viral vector for less than $500. That's in reach of anyone that can snatch a purse.