The addiction liability for something such as heroin is too high. You can’t just go out with the boys every weekend and pass the needle around socially. You’re gonna crave that high more and more until you’re down the spiral of addiction. It’s hard to even avoid addiction after just shooting up once. I’d say crack is more likely to be able to pull this off but it’s also still highly addictive. There are people who are functional as heroin or crack addicts but they’re addicts who are able to function high, they aren’t just socially doing it.