It's legal in so many places because there's no synthetic (or safer) alternative.

Also: Psychedelics should really be limited to use with a professional. The dangerous aspect of possibly going irreversibly insane has in small part to do with why it's illegal. Shit is like a medication more so than the party drug everybody uses it as. Prolonged use has a high chance of causing symptoms similar to schizophrenia later in life. Re-wiring the brain repeatedly is not as healthy as they make it out to be. The increase in intelligence they brag about has a stupid low chance of happening and isn't permanent.

Meanwhile, you need a shit ton of alcohol over a long period of time to cause the damage they're talking about. The occasional beer or sip of wine isn't gonna kill you by itself. If you have to drink it everyday you have an addiction, but banning the stuff because a few people like it too much is absurd.