What are some ways to argue with a hippy who thinks hemp is the panacea that would save america if legalized?

He said the exact same thing I've been hearing for years. It would be great for ropes, paper and clothes, and that it would single-handedly preserve our economey and be a staple of our future success. Why do filthy hippies try to argue the capitalistic angle anyway? Anyways, I need rock solid evidence that disproves beyond a shadow of a doubt that legalizing hemp is a legitimate way of saving the american dream and is infact what its always been. A pipe dream that sounds reasonable when high just like candy flavored broccoli and magnetic dog dogwalking rails, or building a bong out of a microwave.