Medical literature and talking with people who have done these things and knowing about their usage afterwards. Particularly people who have done lots of different drugs and isolate a few things as just different.
One of the disservices done to young people being taught about drugs is the misrepresentation of the addictive quality of various drugs and lumping everything together.
Sibling comment explains it well enough, but from my own experience: you don’t mess with a few, select drugs. You just don’t. There’s potent synthetics that you can rid yourself of despite their addictive nature. But I don’t know anyone that wasn’t messed up by CM. Honestly, there’s a few drugs you simply shouldn’t bundle with the rest, they’re not even drugs anymore, but pure brain hijacking material.
Why do you think that's true?