Heh heh. When I was growing up there was a big push to prevent kids from smoking, because smoking was supposed to be the gateway drug to marijuana. When I got to college I heard the same thing from all the smokers: "I never had any desire to smoke cigarettes until after I started smoking pot."
likely a result of its questionable legality, since cigarettes are a perfectly valid reason to smell like smoke.
I wonder what percentage of legal opioid users move onto heroin and obtaining the drug via illegal means. If more, then at very least the theory is applied in a hypocritical way.