Why do you think teenagers start doing drugs? Or drinking? Or other self-harming behaviors? I agree (with you), some do engage in it just for experimentation, or for thrill seeking. However, there are those who do it to ease troubles, numb pains, and to cover up struggles.
I want to offer some understanding of why adolescents do drugs and alcohol. Explanations not excuses, because there are other ways, healthier ways, of handling anger.