There some evidence that nicotine may be inadvertantly used as a self-medication for schizophrenia and/or adhd

Cocaine is a party drug afaik, I'll give you that one.

Hallucinogens have the ability change people's perspectives on the world, often for the positive. Now the current psychiatry lens is you can only have "medicine" if you have a "disorder" but that doesn't really seem to make sense. Why can't you take medicine to move something from average to above-average? So I agree it's not prescribed for treating many disorders, but that doesn't mean it isn't therapeutic.