What are you talking about with your second paragraph? I can't tell if it's supposed to be an analogy or whether you actually think everyone was smoking opium back then.
Yes, the ancient Greeks were smoking opium. Nobody said that "everyone" was doing it, but its use was pretty widespread in neolithic Europe even before Sumerians were cultivating poppies Mesopotamia, back in 3400BCE.
Worth noting that people were smoking plain old opium back in those times; I'd be reluctant to apply their reasoning to fentanyl.