I think there's a lot of good points here. I also think cultural acceptance is a big part. Here in the US, we have music, television shows, movies that help to create a culture of drug use. I remember in high school seeing the "emo" or "goth" type kids smoking and that kind of addictive behavior could potentially lead to worse problems in the future even though some see it as "cool". I don't recall any songs or genre like rap even mentioning drugs in East Asia. And I'm guessing because teens are more impulsive, they're more vulnerable to falling through the cracks than an adult.
I know in some parts of Asia, if you even BRING marijuana to their country, you will be jailed for life. The social stigma against drug abuse is very strong there and the penalties very harsh. Maybe I'm wrong but other countries I imagine resort to the death penalty as an option too. I would think that because Asian countries are more dense and urbanized, they have to be more strict to maintain public order. When you lay severe punishment on an activity, that activity becomes taboo in their society and no one dares to try to abuse drugs. In the US, we're much more acceptable of drug abuse and provide more gateways to start abusing. Harsh penalty systems do seem to work in other countries but I doubt Americans would have the stomach to take such extreme measures to solve the addiction crisis.
Lack of social support, poverty, unemployment, depression, peer pressure, stress, inability to cope, little to no access to mental health or counseling, (maybe because of no insurance or no money) are just a few reasons why people may start abusing drugs. I'm sure most people would not want to abuse drugs but they fall into a hole and it just becomes something to look forward too. I hear that more rural, impoverished, high unemployment communities are experiencing more drug abuse.
I used to blame just the individual and that it was solely their weakness for abusing drugs and would look down on them. But I feel the system and culture in the US has failed a lot of people and is more responsible for abuse and addiction. We're so used to having quick fixes and convenience to solve our problems and drugs play a part in that. We also prescribe a crap ton more narcotics compared to other countries exposing more people to narcotics and increasing the number of addicts. I think also the fact we share borders and are relatively closer to Central/South America exposes the US to more drug trafficking than other countries. I blame the system more because the system is also responsible for the high rates of obesity and diabetes rampaging throughout the world now too. People who stuff themselves with sugars and additives are addicted in a sense too right? Often cause we advertise it, glorify it, supply it cheap and just love stuffing our faces. And fixing the system would solve the problems more efficiently than fixing and blaming every individual. I feel it's easy to fault individuals because then we can feel elevated and above others when often it's because we're just fortunate to be born to good parents, raised in a good neighborhood but that doesn't solve the problems our society faces.