I would argue its a combination of miserable life circumstances and lack of availability of better options. Have you ever heard of the drug Krocodile? It's most prevalent in Russia, a cocktail of horrible chemicals cooked down with a little codeine. It's a death sentence if you use it for a year, and not a nice death either (consider this a massive understatement). Even the people who use it know this, they just lost the will somewhere along the way to care.