I don't believe we live in such a depressed, suicidal society that people will turn SO en masse, to a drug that has nothing to offer the user except death.
Drugs cost money and people that have no money, have no drugs, and when they DO start to make money, they kind'a LIKE it, so they stick around to keep makin' it.
I see it all the time.. trust me.. I see it in the morgue, I see it in drug testing.. stone cold facts. Drugs costs money, or other things, like prostitution. Why do you think welfare recipients sell their free food to convenience stores? The welfare we provide addicts with is being sold for drugs. They do have the money. I see it, ask your local LEO.
Actually heroin is dirt cheap these days. I personally know too many dead and not dead yet junkies. All of them got there using recreational drugs, not through a MD.