The term "rite of passage" is very fitting.

I've been thinking about this stuff all day, and trying to figure out how to reconcile the potential rewards with the dire risks involved; should I recommend dabbling with this crazy mojo, or should I tell people to leave it the hell alone and not to risk it?

I suspect some of the appeal for those of us who've been down this path, especially when young, was the risk itself; because "we are a generation of men raised by women," and we wanted to test ourselves against every boundary we could find - even the borders of reality itself, if we could find them - and to be tested ourselves.

I suppose the socially accepted alternative is to get as drunk as you can and pick a fight.

What you say about indigenous peyote and ayahuasca users is very true. This is a very different use pattern from U.S.-style recreational use. For one thing, non-shamanic users are using doses that we'd consider sub-psychedelic, at least most of the time. The shaman knows the person and if he or she is ready before a person is taken to a level that would be considered "tripping" by our standards. People are only taken to that point when they are ready and know what to expect. Still, you're right that these practices (indigenous/religious psychedelic use) are not especially harmful-- a lot safer than our cultural institution of heavy alcohol use.

The illegality of these drugs, in my estimation, actually encourages irresponsible use patterns, through hard-to-control dosage and intermittent access. There's definitely a mentality of "trip hard now because you may not be able to get this stuff in a year" in the U.S. psychedelic culture, and the drug laws are culpable for creating it.