1000s of people dying every year from drug overdoses in the US would disagree with you. In fact heroin and meth, both deadly and dangerous drugs, are used far more often than psychedelics I would bet.
Also note that what I've meant was essentially about treating psychedelics the same way as opiates, not much about meth (which can be deadly in an indirect way (it doesn't kill by itself but given some time can easily screw a weak mind to the point of madness) for many people) nor about heroin (which can kill you quite literally). Nevertheless in both cases there always is a choice people are given many chances to make and in case of black market fentanyl there almost isn't.
I don't think "purely psychological" is implied by different people having different susceptibility to addiction. If it were purely psychological, wouldn't that imply a person could become addicted independently of ever taking the drug?
It is also important to emphasize that that's about just a single class of drugs you've mentioned. Popular psychedelics, although able to induce even stronger sensations usually don't cause even psychological addiction (although there are some rare people who start taking them every weekend, a normal person will hardly feel like repeating the experience soon and any kind of regular - it's just too intense psychologically and there also is tolerance, the acid wears off in some hours and won't really work until the next week) and (except some of them) hardly cause any harm (unless you're a psycho already - then you may happen to go nuts completely) or hangover. Opiates, at the same time, don't make you bright but just give a strong sense of relief kind of "I just feel good and uck everything absolutely" yet cause powerful physiological addiction, severe hangovers and serious risk of lethal overdose.