Addendum to my prior post: Pretty much like LSD. I've taken LSD about a dozen times, but I was always a little bit scared of all drugs. When everyone else was taking one hit, I was quietly cutting my blotter in half and then testing out how it would affect me. If after an hour, I was not on the verge of losing control, I would take the other half. I would never take more on the same night, even if I had it. And I never had a bad trip!
However, there were couple persons I encountered who were like "If one hit is great, imagine how taking four will be!" The rest of us would say, "No man, don't do that, please. Srsly, don't fucking do that?" And they'd fucking do it anyway, and then end-up in the ER with LSD psychosis. Or it would ruin half the night as we were trying to keep the guy from freaking out or jumping in front of cars.
All the "bad" shit you hear from PEDs are from the personality types like the aforementioned "Four hits must be 400% better!" guy. Fucking idiot.