When I first joined the force, I thought it was about supply, and to the extent that you could curtail that supply, I reasoned, you could restore some order. That is not entirely untrue, but that approach does not do anything to address the demand for illegal substances. The drug dealers exist only because their customers keep buying.There is a huge amount of undiagnosed, self-medicated mental illness in our society. We no longer have the institutions necessary to deal with those, so many sufferers end up in prison.
What first drives people to experiment with drugs, and why do they keep returning? Aside from basic physical addiction, they keep coming back because, on some level, the drugs are working for them. They are meeting a need. They are blunting a pain that feels too overwhelming to contend with. Or they are medicating a mental illness that, in a world that still stigmatizes mental illness, has gone undiagnosed.
Prison keeps the mentally ill off the street (for some limited period) but does little to identify and treat their underlying pathologies. See my recent rant on our non-treatment of mental illness here.