I think it increases consumption if anything by making it cooler. It's hard to imagine anyone would do coke if it wasn't illegal and cool because of it's legal status.
Well, back when it used to be legal a lot of people did do it. Also, it caused so many problems that a movement started to ban it.
[cocaine] caused so many problems
Like what?
India vs. Pakistan: the nuclear option is dangerously close, and nobody seems to want to prevent it
http://qz.com/541502/a-nuclear-war-between-india-and-pakistan-is-a-very-real-possibility/