I've had a relative's life recently destroyed by secretly using marijuana
I will preface this by saying that I do not make recreational use of any pharmacologically active substance, and I strongly disapprove of recreational drug use. And I have never understood the appeal of such use; on the rare occasions when I have had even a slight buzz, either from a particularly strong prescription or from one occasion when I downed a triple-dose of cough syrup by mistake, I found the sensation of being in less than complete control of my senses to be one of the most revolting I'd ever experienced. (And when I get a colonoscopy, I explicitly request that the sedation be kept light enough to keep me conscious, lucid, and able to enjoy the guided tour of my lower intestine; at the last one, the doctor was good enough to narrate, and I
never did pass out.)
That said, out of the four biggest "killer drugs," the four that have, over the course of Human history, caused the most morbidity, three of them are highly addictive, eliciting tolerance, physiological dependency, and painful, and sometimes life-threatening physiological withdrawal. The exception is cocaine: a killer, to be sure, but not exhibiting those characteristics, at least not to the extent of the other three.
Out of the three most addictive drugs, all three of them killers, all of them undisputedly causing severe physiological addiction, two of them are also the two biggest gateway drugs, i.e., they lead to other, unrelated drugs. The exception is opiates and opioids, as a class. They generally only lead to other opiates and opiods.
Out of the two biggest gateway drugs, both of them highly addictive killers, neither is currently illegal for adults in the United States (and most other countries), one of them has
never been illegal for adults, although it has lost much of its social acceptability (and is highly restricted in most public places), while the other retains its social acceptability, and is occasionally still the subject of positive health claims (such as the absurd notion that it is necessary for proper absorption of certain nutrients). What are these highly addictive killer gateway drugs? Ethanol and nicotine.
Marijuana is not even on the radar here. Neither, for that matter, is LSD.