Social scientists back in the '70s did an experiment with rats where they looked into how much environment factored into their propensity to become addicted to drugs. One set of rats were isolated in small cages with no social interaction. The other set were in "rat park" where they had other rats to interact with, toys to play with, and room to run around. Both sets of rats had the option of drinking plain water or water or water laced with morphine. The isolated rats were far more likely to drink the morphine-laced water and become addicted than those at "rat park."
Morphine is a powerful pain killer. People in pain seek out something to alleviate the pain. People not in pain might try drugs such as morphine as a recreational drug, but generally don't get addicted. But people who are in pain — either physical or emotional — are far more likely to become addicted because when you take away the drug, the pain comes back.
In the "rat park" experiment, the isolated rats experienced the pain of loneliness and boredom, and the morphine-laced water relieved that pain, so many of them became addicted.
Social scientists also studied drug use by military personnel. I think it was a study of injured soldiers and their tendency to continue heavy drug use after they recovered from their injuries and re-integrated back into society.
The soldiers who had healthy social support networks and career opportunities tended to give up heavy drug use once the physical pain was gone. But those who came from dysfunctional families, poverty, and generally unhealthy environments were far more likely to continue drug use and in many cases become homeless or suicidal — even when their physical injuries had completely healed.
Before going off to war, soldiers might have internalized their pain. But in the military, they discovered the pain relief that opioids provided. While on the surface, they appeared to have recovered, the psychological pain that was present even before they were injured was still there.
So the answer to drug addiction so prevalent in society today is not removing access to drugs; it's figuring why so many people are in such debilitating emotional pain that they resort to heavy drug use.