After binge watching hundreds of hours of police videos and journalists that ride with police I would lean towards prescription pain killers being the root cause. Doctors prescribe a powerful drug. The prescription expires. They turn to street alternatives Fentanyl at the moment. They are now zombies. Getting off of Fent is near impossible for most so they are run through the system. It takes 6 months of being in treatment to get 89% of people off that drug. Keeping people in treatment that long is challenging to put it mildly. According to law enforcement the only things making a difference are NARCAN and blocking Fentanyl from entering the country.