For me, honestly speaking, psychiatric pills were the "gateway drugs". And, of course, alcohol. Extrapolating from a) they give me strong drugs on prescription which gave me even addiction and withdrawal (first drug ever was lorazepam, 3 months straight with 2-3mg/d for social anxiety, then switched to other ward with other quack which decided I'd be on the way to addiction (true) so he stopped cold turkey (wrong) and I got zero preparation or help for the panic hell which followed. And b) Alcohol is fun and freely available, this together with people in the ward reporting from their beautiful experiences with shrooms, MDMA and weed, I decided that the prohibition people can't have the absolute right on truth and decided to make my own experiments with whatever drug crossed my way. First one was DXM, as an OTC drug. Thankfully, or maybe sadly, it wasn't DPH - that one might have repelled me. But DXM was heavy, dirty, and great fun, and relief - it provided me with the first real antidepressant effect when the drugs the psych docs gave me didn't really work. Turned out I have therapy resistant stuff like many others out there and dissociaties happen to lift that therapy resistant stuff.
So far I've done the whole range of drugs, from opiates over psychedelics to GHB and stims, and of course the class which happened to really get me were the opioids, yet still it wasn't what I expected, I expected a panic hell comparable to benzo withdrawal mixed with diarrhea and vomiting and a feeling of dying but, as long as one used orally maybe, it's really more of a (bad) flu. No anxiety, not even so much of loneliness, but apathy, weakness, great restlessness and yeah, diarrhea but that's the easiest to treat with loperamide.
Other class which got me were the dissociatives but that was my own fault, I began to consume without any judgement after my first long-term gf dropped me out on street after something which might have been a psychotic episode from a tainted batch of MXE. Never had anything similar before or after but this days were so weird. And then I come out of three or four days of isolation just to realize my life has gone to the bahamas and I've been left there alone (suffering from heavy social anxiety my gf was the only real contract I had in that time, no job either) so I began to use what I had in mind to work: dissociatives. With some common sense much of that stuff which followed wouldn't have happened and certainly is similar shit possible with alcohol but in worse because on alcohol one can actually damage stuff by e.g. driving drunken and the withdrawal can kill you.
I'm for a full legalization of all substances, with a staggered model for access, e.g. soft drugs are free for adults while harder drugs require sort of a "drug license" where one needs to attend an introduction course of dunno not much but maybe 2-3 hours about side effects, risks, safer use and all that and of course the availability of addiction counseling (maybe they could make an addiction insurance, lol, where the money from drug taxes goes into a fund to help with addiction) and protection of minors.
This would also dry out a huge income for organized crime, as well as cease the need for a huge amount of people to do illegal shit because of addiction, self medication needs or plain desperation.