I know a kid whose throat swelled up, couldn't breathe for several minutes, and suffered brain damage after a one time incident of eating peanuts... Apparently, non-negligible (over 1% [1]) portion of the population reacts this way.
Lesson for everybody: Don't eat nuts!
[1] http://www.mountsinai.org/about-us/newsroom/press-releases/r...
Your argument against psychedelics is not persuasive in the manner presented.