When I was in high school, I excelled in math and science, so I was pushed super hard to go into engineering for college. I ended up changing majors eventually, but holy shit did I not understand just how strong the engineering school -> “defense” industry pipeline is. They recruit engineering students hard
It was an eye-opening experience, realizing just how many people were comfortable working for these companies as long as they got a fat paycheck
It is pretty much just scaremongering. Marijuana, like any drug, can put a person in a mental state that can serve as a trigger for a psychological condition that someone is prone to, like if someone with a family history of anxiety gets way too uncomfortably high. It’s not necessarily the drug that’s at fault - it’s having a stressful experience of a bad time. I’ve never heard of psychosis induced by cannabis though.
Marijuana is just about the safest drug there is, and I think most people could safely try it with no ill effects.