Young people are not as smart and wise as you.
Most people are sinful by nature (excluding those who are perfect). They self-medicate because adolescence is a painful and disorienting experience for some. And then there's exploration and the herd instinct (i.e., peer pressure).
My man, you misunderstand my comment. OF COURSE I did stupid stuff as a kid; we all did, and likely most did this. My comment was directed at those who continue to do stupid stuff, as was the original post. Happenstance poor judgement is easily understandable - repeated poor judgement, not so much. Being a stupid pothead requires dedication to failure, which is where my comment was directed.