I don't view meth as the source, but a symptom of the economic situation(hopelessness), which then causes further socioeconomic decline in the pursuit of more drugs.

Drug addiction, for many, is trying to fill a hole. That hole could be poor choices leading to a bad situation, absent or abusive childhood relationships, a self esteem model that has been largely destroyed by the culture that person lives in, a lack of role models, many things. They can be internal issues that the individual is primarily responsible for, or external issues that are the result of being dealt a bad hand in life. Most likely a mix.