I'd probably blame that kid's parents. Use of hard drugs is highly correlated with abuse of some kind.

For example, Biden is a pedophile & Hunter is a crack head who sends his homemade porn to his dad.

Maybe in your friend's case the abuse wasn't sexual, but instead emotional or physical. Or maybe the public school system was the source of abuse. But either way the parents failed their kid. A parent has no higher responsibility than to teach their kid how to deal with the world. Someone who turns to heroin is trying to escape because they can't deal with anything.

Whether something is illegal or not really doesn't matter. Making alcohol illegal made societal problems caused by alcohol worse, not better.