A lot of addicts first started out with chronic pain - back issues, work related injuries, surgery recovery, etc. Once you're in pain, you quickly feel self pity, depressed, unmotivated too.
Those opiods sure do work wonders and make you feel great, but if you stop popping them then you got back into the painful slump. So you keep taking them.
Remember, outside of the DC bubble, there aren't any/few resources to help people curb themselves. Do you think west Virginia MeMaw is going to be motivated to consistently go to physical therapy each week, for example, to help her chronic back problem or woukd it be easier to just pop a pill? Or tell her doc that her back feels better so no need to refill her prescriotion?