I think by the time You've lived a 'few' decades, we all encounter our own experiences with addiction. It's impossible to not encounter it nowadays. Again I agree with NUG...if you are on a path to addiction, alcohol and cigarrettes, I would bet, are more the culprit than Marijuana, simply because kids see it used by their parents since they were born. They are not 'stigmatised' like MJ is, ('Gateway drug', leads to Cocaine and Heroine), so the kids expirement there first with their friends.
I have said multiple times, that I am not a 'big' drinker. The main reason for that, is my brother and sisters and I grew up in a household having to witness the repurcussions of an alcohol addicted, 'angry' drunk for a parent.
He never confronted, or admitted to it as a 'problem'....in fact the holes in the walls that he would punch...as a family, we would just ignore them, and my Father never even attempted to repair them, even though he would say, he didn't remember making them (we finally had them fixed for our Mom a couple decades ago). Perhaps, we left them there as a reminder of the consequences of alcohol abuse.
I fully understand the consequences of substance abuse, in this case, the legal kind. and in all my years of living, I have never encountered the rage and destructiveness from an MJ user that I witnessed from the abuse of acohol. So 'at least' I'm not speaking without my own experiences on the subject.
(My encounters with the Cocaine addicted are far more dangerous and scary... Rarely have I seen people transform into monsters...fiends really, as I've witnessed with 'Coke heads" needing a 'fix'...
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... and these encounters didn't happen in a back alley.... Most of these encounters were when I attended Catholic school into college....so ya, not only homeless, drug abusers. It can happen to children of affluent, well to do parents too....)