I lived for years right by the Haight entrance to GGP. I wouldn't call the participants in the drug scene there hippies. There were a lot more crusties and gutter punk types, along with stereotypical thug dudes and tweakers. A lot of people were really aggro and there was some sort of fight nearly every day. A friend of mine would buy her pot over there and her dealer was a clean cut looking late 20s guy from the avenues, who used a cane because he had been shot in the leg. Gun violence didn't seem very hippie to me, either.
One of the odder things to me about the area (everything was odd to some degree, including my presence there) was that there was so much drug activity right next to the police station.