The Vietnam story is definitely an interesting datapoint. They went to Vietnam, had easy access to heroin (it was a war zone, certain civilian rules no longer applied) and fell to the vice. Not sure why you discount the possibility that the primary motivations of cold turkey quitting heroin were the elimination of easy access to heroin and the stigma of living the rest of their lives as heroin addicts.
Prison for drug use is cruel punishment, but therapy & community service (hello Portugal) are entirely reasonable (and effective!) approaches to the problem.
Prison for drug use is cruel punishment, but therapy & community service (hello Portugal) are entirely reasonable (and effective!) approaches to the problem.