I'd be willing to bet that they were milk drinkers. Those junkies probably ate tomatoes, too. Gateway drugs, all of them!
Correlation does not equal causation.
The issue of recreational use of marijuana vs gateway to harder drugs is beyond dispute. There is a direct link to the use of marijuana and the transition to harder drugs.
I will stipulate that not everyone who uses marijuana recreationaly instantly graduates to heroin.
But the idea that marijuana is harmless is also nonsense. It has more carcinogens than tobacco, and is much more cognitively debilitating than alcohol consumption.
In the case of tobacco one does not drag a cigarette/pipe/cigar the way one tokes a joint or inhales bong hits. These are much more deep penetration of the lungs and are held until most of the smoke has dissipated/absorbed. This may be related to the relative price differential and will concede this point. But with marijuana “the stronger the better” , and the fact nobody’s selling Panama Red “Lights” with lowered tar and THC speaks volumes.
In the case of alcohol, one may be hung over for a day from a good buzz, but the effects of marijuana last much longer and impairs the cognitive function for up to a week for a single use (a good buzz) and much longer for regular users.
There is a causation effect to marijuana and harder drugs since the purveyor of one, is also highly likely a purveyor of other illicit substances.
Nothing good comes from legalizing recreational marijuana, anymore than would come from legalization of recreational Quaaludes, LSD, heroin, etc.
Legalization is a bad idea no matter how you try to paint it.