I find threads on this subject entertaining. Many try to address the subject, but few can speak from knowledge, training, or experience. I can’t get worse than that, so here’s my shot at it.
Hashem created poison ivy. To date, there is no one with any clue what benefits it has. We finally watched the pharmaceitucal industry take botulism toxin and render it useful as Botox, a medication. One day, we might see more than a drug, Marinol, produced from marijuana. Till then, it should be illegal, its users sentenced to treatment, and its dealers imprisoned.
The long term risks from MJ are frightening. Study the science a little. Some earlier commenters mentioned the effect of turning stupid. True. How about all sorts of endocrine problems (hormonal disruption)? Of course, MJ can ruin the years in which a human being is doing most of their social and intellectual growth. No wonder some countries like Japan, where MJ users are eliminated, produce far more than United States.
I’m not familiar with Rabbi Aryeh Kaplan’s writings on this. But no one can proclaim that Ketores included Kinai Bosem (assumed to be the origin of the term cannabis). The posuk never mentions this in the ingredients of the Ketores. It is mentioned as an ingredient in the Shemen Hamishcho, which was used for annointing. It was not burned, and no one absorbed its smoke. This myth is one of the oldest in the Jewish addiction discussions, and it is baffling that the blind belief in this persists.