You might want to take a look at the situation regarding "Heroin overdoses" in those countries which have legalized its use and possession.
In April 2021, the Centre for Disease Control has estimated that the number of people in the USA who had died from overdose in the 12-month period to the end of September 2020 was 90,237.
...
There were 4,393 drug poisoning deaths registered in England and Wales in 2019 – the highest since comparable records began in 1993.
“Almost half of all drug-related deaths involved opiates such as heroin and morphine. However, cocaine deaths rose for the eighth consecutive year to their highest level,” the Office for National Statistics’ report said.
That makes the US rate around 270/million and the "England+Wales" rate around 74.26/million. I'd say that a reduction in deaths by about 72.5% indicates that there is some "slight" correlation - wouldn't you?
Or you might want to read "
How Europe’s heroin capital solved its overdose crisis" to see how Portugal dealt with a drug addiction problem that was even worse than the one in the US.
PS - Did you know that, when Bayer resurrected CR Alder Wright's morphine diacetate in its search for synthetic Cocaine. When tested in the Bayer labs, NONE of the test subjects became addicted to the new drug (which Bayer patented under the trade name of "Heroin") and it was sold "over the counter". At that time it was not known that there is a percentage of the population that is "Heroin Addiction Immune" and it just happened that all of the test subjects that Bayer used fell into that category (drug tests were conducted on MUCH smaller test populations in those days).
PPS - None of the above should be taken to mean that Heroin is NOT addictive, it is. It just isn't the crushing killer that the media like to portray it as.
PPPS - Drug addiction, like alcohol addiction, IS a "coping mechanism" because it allows the addict to [1] forget about their underlying problem(s) for a while, and [2] blame the substance that they are addicted to for their inability to cope with their underlying problem(s). Addiction, however, is NOT a very productive "coping mechanism". "Going dry" WITHOUT dealing with the underlying problem(s) generally results in the substitution of one (non-productive) "coping mechanism" for another.