Much of the country is not that rich at all, especially once you get to central parts of the country where industry has fled leaving people with odd jobs and insufficient healthcare. The opoid crisis centers around parts of America which are the hardest hit financially: http://edition.cnn.com/2016/09/23/health/heroin-opioid-drug-...
Finally, there is also something about expectations. For my generation, we grew up hearing "work hard, study hard, and you will live a good life, own a home, enjoy the life your father and grandfather lived." Except that formula does not work anymore -- industries which worked for our parents got offshored and we're now competing internationally. An entire generation still holds the expectations of an American lifestyle, buying a home with our 8-5 factory job, having barbecues in our backyard, playing "Where the Boys Are" but that expectation is no longer valid for all, leading to unmet psychological contract an entire generation expected to live.