Surprising the degree of relatively un-informed opinion here on this subject.
Here’s some anecdotal input (not without some theory):
Late 1960’s, attending University of Calif., Berkeley, I and several other graduate students used hallucinogenic substances in a rather structured way – weekend evening meal, maybe with some marijuana for starters, then, after dinner, small to moderate dose of some thing like mescalin or LSD (psilocybin is a bit more exotic to acquire, but reports from those familiar with it were that it’s in the same ballpark with peyote and LSD) . Then an evening (usually well-into the night) of listening to and discussing music (we were all in the music-history department). Quite productive. At least one notable PhD dissertation came out of that group and the things discovered with some help from ASCs (altered states of consciousness).
Stories about bad experiences, especially afterwards… The thing is treating the whole matter with respect and skill. No one I knew went into such experience without, initially a “guide” – someone a) personally trusted, and b) experienced, also having been guided / trained. What happens during, and after is a function of what’s already in the person’s psyche, how stable and open-minded they are going in; it can’t be blamed on the substance (referring to the common hallucinogens, not hard narcotics, amphetamines, or other exotic chemical concoctions).
Aspects of such experience are clearly comparable to aspects of (hard) jhana. (This is not equating them, please note.) For one thing, the mind gets to experience a shifted perspective, a kind of awareness radically different than every-day conditioned worldly consciousness. This can help one recognize how fabricated our conditioned “reality” can be. Particularly at about graduate-student age (early 20s), one can get a glimpse of one’s conditioning which one has just worked hard at for ca. 16 years of “education”, and of the possibility of it’s being modified. Compare the tradition in some cultures for a young graduate to go live abroad for some time (e.g., I believe in some European upper-class traditions). Experiencing how other people live, think, work, dream etc. in a different culture, different language, etc., one can see how, in a sense, one’s own culture is also “other”. That’s called education – “e-” (ex- out of) “-ducation” (being led).
About the same time, the German composer Karlheinz Stockhausen was teaching in the San Fransisco area for half a year. His attitude was to recognize, but discourage using a drug. He said one can achieve the same with good training and hard, concentrated work (e.g. that of composing and performing music); and then it’s an authentic skill (you own it). (Listen to Stockhausen’s music, or see him lecture in youtube videos – the dude was concentrated!) The use of a substance can help one realize that there’s something possible not previously recognized, which then can be authentically cultivated.
With such things, wallowing in it, or addiction, attachment, etc. – are more functions of the person’s own state of mind and training (or lack thereof) than inherent in the substances themselves.
I believe those experiences played a role, next to long cultivated experience with music itself, in developing skill in concentration, and, some 40 years later, being more inclined towards appana-samadhi (i.e. a samadhiyanika). (The kind of enhanced concentration as in some hallucinogenic and musical experiences is more of the khanikha-samadhi sort; not, though, vipassana-khanikha-samadhi, which is a highly advanced training.)
Bit more: playing with such mind-alteration earlier (adolescence) is ill-advised as the mind is still being conditioned (to carry-out normal social-cultural roles). Too much “tripping” damages that. Also, with longer life-experience, forced mind-altering is less attractive; healthy people naturally give it up after that period of youthful experimentation.
Also, there’s the famous, perhaps apocryphal, story where the Beatles (mid-20th-century pop-music group) went to their (old) guru in India and gave him LSD or something, with high expectations; the guru took it, just sat there, eventually remarking something like “So What?” (nothing new to his mental powers).