Because it's $5/hit.
Because there are cities in this country that condone and encourage it by providing supervised injection sites that are taxpayer supported and funded. Tell me how great that's working out? While we're at it, let's open up a brothel for HIV patients. Can't hurt, right?
Addiction and alcoholism are essentially the same.... same fleas, different dogs. We don't think like normal people think. We don't want one or two slices of pizza, we want the entire pie. Ours is a disease of MORE. More sex, more pleasure, more money, more food, more attention, the list goes on. A few of us are genetically predetermined because of a father or mother who drank or used. Probably more like many of us. But that's neither here nor there.
It is a disease that centers in the mind. So it indeed has a physical component (physical dependency), but also a mental component (mental obsession).
Drug addicts and alcoholics, sadly, would rather meet their Creator in person, because of their disease, than turn their lives over to His care and protection to help treat their disease.
Because honestly, the only thing that works for most people addicted to drugs or alcohol is a direct ENCOUNTER with God.
Otherwise, death awaits them both.