I always thought it odd that Marijuana is named specifically, along with "addicted to".
But to Cole's point, I do think there is a connection between drug use and psychosis, especially among people that start using early. Gun violence isn't the only societal ill that America excels at, I brought up drug overdoses and suspect there are others. There are likely overlaps. Causes are likely somewhere between a few and many, but weed use is most probably below availability of weapons. As per usual, people are looking for simple answers to complex problems.