It seems like the people profiled in the article failed to learn that completely. Instead they go on about plant spirits and vibrations and other things they hallucinated as if they were actually real. That the perception of truth and truth itself are the same thing.
You don't need drugs at all to learn how subjective our own perceptions of reality are. And the risks suggest that it would be unwise to do so.
Like I said, you can waste it, amd lots of people do. Some people go through their entire lives and learn nothing. I'm sure you can appreciate that reading about a rose is not the same as smelling and seeing and holding a rose, though.
You don't need drugs at all to learn how subjective our own perceptions of reality are. And the risks suggest that it would be unwise to do so.