Teenage marijuana smokers have also been found to be less likely to complete high school and more likely to make poor career and life choices.
Correlation does not equal causation. Perhaps people prone to depression and making poor choices are more likely to self-medicate with pot, alcohol, tobacco and so forth.
If youngsters were seeking to "self-medicate" with marijuana then they would be doing better.
What you are talking about is self-destruct.
Correlation does not equal causation? Good red herring there. No evidence is ever good enough for potheads: from brain scan imaging to potheads defecating in parks.