I don’t know about violence, but anecdotally I can tell you every single person I know who has continued heavy pot use over a long period of time has severely diminished mental capacity. Every single one, including some who were once brilliant people.
It is not harmless.
I will agree to that. I have 2 older sisters that just come up with the strangest conspiracy theories. I know its because they are heavy users most of their adult lives. They have somehow morphed every known conspiracy into one big grand conspiracy.
Then I just sit back and throw out other possible theories at them to really twist their minds. The next time I see them they use these same things in their conspiracy arguments.
But they are as tame as kittens.