Sounds like these kids already had a problem if they were psychologically addicted to weed. Could it be a broken home? An abusive alcoholic father? Just not fitting in at school?
Yeah, growing up can be tough. We all have been through such trials and tribulations in one form or another, some more than others, and these kids used weed to escape.
What if they had used alcohol instead? Many do. Any reader here can probably recount a tragedy caused by that, but they'd be hard pressed to remember one caused by weed.
And, by the way, did our fearless Danish researchers (hopefully not in the pay of Big Pharma, but that is very difficult to avoid in this world) look into correlating these cases with social, familial forces that may have had a significant impact: like Dad getting wasted and beatin' up Mom every Friday night?
If you focus a search light on a subject your going to find cracks. There can be no doubt that obsessive behavior is detrimental. How about junk food? I knew a guy with Attention Deficit Disorder, didn't like weed but ate nothing but candy and junk food (probably the cause of the ADD). That crap is toxic as hell, but it's perfectly legal. No studies from Danish people in lab coats taking back pay from Big Pharma (LOL). No 15 year jail terms if you are caught on the bus with pockets full of Snickers bars and Hostess Potato chips. Nope, you can stuff that into you until you explode.
There was once this thing called prohibition. Didn't last very long. Led to some of the worst criminal activity of the era. Thailand appears to be gearing up for that as we speak. Can we spare these good people the inevitable pain and suffering it will cause?
The young need to be educated and steered into productive healthy lives. Everyone has their own path and should be able to find it without coercion and force. And, yes, if you know someone with an obsessive disorder of any kind, including weed, reach out to them and help.