Maybe for some people. I've had Rxs for several opiate pain killers... short-term, but I never opened the gate. I do know more than a few who've made it their life's mission to be under the influence of opiates. This means buying pills on the streets, once they've been cut off. I haven't known any, personally, that have resorted to heroin use, but I think they would, given the opportunity.
It's such a stupid way to die, because the living still have to put up with the doomed user.