What footprint are we talking about? Is it emitting carbon into the atmosphere?
It's that recycling has a smaller carbon footprint than making new copper from scratch. I think this claim is true for copper, recycling v. manufacturing.
At the very least this would increase cash flow in your economy. The cash flow coming from junkies and their newly acquired "free" copper are better off and more likely to spend some of their money on goods other than dope.
Also not a serious argument, but an argument.