Why do people turn to substance abuse? Most of them are from poorer backgrounds. They don't have the education or connections to get nice jobs and get stuck in poorly paid crappy jobs. At some point they just can't take it anymore and try drugs to get away from it all and that's when a new junky is born.
The long term solution is to offer better education to ALL citizens so that everybody has a chance to be part of the american dream. The reality is that promising to put more people in jail is what gets politicians the most votes (criminals aren't allowed to vote) so that ends up being the policy. America, f*ck yeah!