I have a difficult time taking the theory seriously. Does the guy think the money is just going to disappear? That people will intentionally hang onto their money, not give it to banks, and instead "invest" in Kickstarters? Would the Kickstarter people eat this theoretical money?
Amazon gets a cut from Kickstarter. That (might) be taxed as income.
And, from what I understand, many of the larger Kickstarters also have external funding, they don't just use crowd sourcing.