> Maybe I’m missing something, but discussions on the cost of medicine never seem to question whether using prescription drugs is the right choice to begin with.

Because it's pretty darn obvious that once you have Hep C, yes, prescription drugs are the right choice. No one's pumping Hep C drugs into people who don't have Hep C.

> Surely the solution to this epidemic is to address the underlying drug problems first?

I'd recommend addressing both problems at the same time. There's no reason we can only do one.