Nobody said they were the "most astonishing things in the universe" - I'm not sure where you get this stuff. It's another straw man.
McKenna says that neurochemistry, and its material application called "the psychedelic experience," is the most astonishing thing you can personally suppose, or in some cases, even that you can't suppose. But that doesn't say anything about the (real or imagined) notion of a totality of "things in the universe."
McKenna says that neurochemistry, and its material application called "the psychedelic experience," is the most astonishing thing you can personally suppose, or in some cases, even that you can't suppose. But that doesn't say anything about the (real or imagined) notion of a totality of "things in the universe."