Its a cultural thing. America is the richest society on the planet, yet we don't appreciate what we have over here. This is obvious in the fact that even some of the most crime-ridden areas in the United States look indistinguishable from middle class areas. Seriously, most of Compton looks nice as f#ck. I'm from a Cali hood myself and my old way looks hella nice too. People in America don't know what third world poverty smells like let alone looks or feels like. One billion people in the world don't even have access to clean drinking water.
Even though America has the highest standard of living in the world, we have the highest rates of depression. Millions of American people are miserable. Americans, regardless of race, have weaker bonds to family, friends and other people, in general, because American culture places a huge emphasis on self reliance and independence. America can be a very cold place because of this. Add to the fact that our society is extremely polarized along the lines of race and class which drives people crazy. Asians, Africans and Latin Americans put a much higher value on family and community than Americans of any race. On top of that, America is a spiritually impoverished society. Weak bonds to others and a nonexistent relationship with God is setting the table for people to abuse drugs and alcohol as an outlet. In addition, the current fukked up state of the economy is causing people to turn to alcohol and other substances as an escape. America has the widest income inequality in the developed world, so countless numbers of people who can't "make it" for what ever reason end up becoming professional drug addicts.
Also, America is a country overrun by unhealthy addictive products which contributes to a comparatively lower life expectancy. Think about it. Almost everything legal is unhealthy and insanely addictive. Many people work sedentary jobs and eat nothing but fast food. This is the reason why the obesity rate has skyrocketed in the past thirty years. Alcohol, the most used and abused legal drug in America, has also been proven to be the most dangerous drug period, worse than even crack and heroin. Millions and millions of life spans are shortened due to the ac right. Cigarettes are extremely addictive and will give you cancer. Soda tastes good and is very addictive but will give you diabetes. The list goes on. The American lifestyle can be toxic and unhealthy.
The truth is that if more American people had a strong relationship with God and had strong relationships and friendships with others, there would be much less drug abuse in this country.
But the opposite is true. The divorce rate is hella high, a huge percentage of Americans don't have any close friends and our society as a whole is deeply agnostic and borderline atheist.