Side point--your finding that violent criminals typically have used marijuana and other drugs does not mean that nonviolent people who use marijuana use other drugs as well. Those are two different populations.
Both populations are suffering in mind, spirit and in personal behavior with the illegal drugs.
You basically have to be a fool to get into drugs like that.
If people know you self medicate, they lose all respect for you unless they are another doper.
Your parents spend the rest of their lives probably praying for your salvation from drugs.
Not exactly peace of mind for the parents.
Not a dependable person to form a family unit with either.