You're interpreting the word "gateway" too literally, True Religion. It's not a component of grass that would ever make someone buy or experiment with cocaine. It'd simply be the same curiosity that caused them to drink or smoke weed in the first place. That's what people mean by "gateway," and those of us who believe in the gateway effect are simply saying we believe it has to do with the spirit of adventure and curiosity that prompted experimentation with previous substances.