Your science, liberal political science, buried with a complete lack of research, disagrees.
You, or any individual is still faced with that first moral decision. The buck stops there. Certainly, there are those seduced by opiates taken to ameliorate pain after trauma. Been there, done that. Been shot, hit by shrapnel, stabbed, heart surgery, cancer surgery, used morphine, demerol, assorted oxi compounds, and other goodies. Each time, I assessed myself, and I decided to stop taking them, and did so. Those drugs are all seductive. It wasn't easy, but doable. It is a decision. And I am no superman.
During the 1960's Britain experimented with legal heroin for addicts. The addicts had to register, take a weekly class for stopping use, get a job, received the heroin for free. Within months, the addicts were employed, functional, out of the subculture, not committing other illegal acts to support their habits. Research showed, absent the junkie detox as many times per day a fix was needed, and the lack of adulterants found in the street supply, the addicted became healthier, and even showed a retardation of the aging process. Certainly, no one wanted them operating heavy equipment or driving school buses and taxis for a living, but menial and office jobs, went well. The number of new addicts decreased drastically, because there was no profit to be had enlisting new addicts. The American DEA found this abhorrent. American politicians started lobbying the British government to revert the laws, with threats of noncooperation and withdrawal of other benefits, as well as trade sanctions. The program ended. Addiction rose, crime rose, people suffered and research stopped.
It was the American intolerance movement, the same movement that led to prohibition, along with lies from politicians and bureaucrats like Harry Jacob Anslinger that made former over the counter drugs like opium, marijuana, cocaine and so forth illegal. Always on the basis of morality.
Feel free to go with science, I prefer honesty. Government doesn't give grants for honesty. People make money selling goods to police forces and prisons that wouldn't be needed. Yup, marijuana, the gate way drug that leads to REEFER MADNESS.
Some people are weaker than others, but people like you need to stop giving them excuses for their own immorality.
It would far less expensive for our nation to buy the entire world opium harvests, than pay for interdiction, imprisonment, associated crimes, law enforcement, security guards at prisons, and so forth, give heroin away for free to registered addicts, burn the balance that has no medical use, but somebody or somebodies are making a hell of a lot of money keeping heroin illegal. You want to stop the abuse of synthetic opiates, put a cap on how much can be produced by the big pharma companies that make those synthetics. Figure out how much is really needed for medical application, and stop the manufacture of the rest. Don't tell me synthetic opiate production by companies who do know their excess production will end up on the streets is a disease. Cut the BS, stop enhancing the lies about who is making so much money off human depravity. We'll never stop the manufacture of bathtub meth, or overseas fenatyl, but we can kill the entire drug subculture by making it all legal, controlling the supplies as best as possible and eliminating the profits. It is a set of moral problems. No excuses for anyone. Eliminate the "forbidden" in fruit and see how the problem disappears.