Isn't the very term "drug abuse" granting that same conceit, though?
I don't mean to be pedantic; I think it's a very good question: Where does "drug use" end, and "drug abuse" begin? Depending on where that line is drawn, I think it might very well be the government's job to "fix" you if you slide into drug "abuse." Especially if you start posing a danger to others.
Of course, in many cases, the term "drug abuse" is used to mean any illegal/off-prescription drug use, which is ridiculous in itself.