To blame pot smoking for mental illness is about the same as blaming Tobacco smoking, drinking chocolate or taking in a caffeine products.
To blame any one thing as the cause of mental illness is impossible.
Much of the cause of mental illness can be traced to genetics...with or without outside influence accompaniment.
Many things can be a"trigger". An event, a family/environmental situation, drugs - of any kind, alcohol.
There are no absolutes in anything and while marijuana use
may be a trigger, I seriously doubt it is the
sole cause of mental illnesses.
And no...I have never, ever tried marijuana, not even a puff.....yet, I have depression issues, as do several family members, past and present.