income tax revenues are highly inelastic to the top tax bracket rate

Via Division of Labour, "You Can't Soak the Rich" by David Ranson:

The chart nearby, updating the evidence to 2007, confirms Hauser's Law. The federal tax "yield" (revenues divided by GDP) has remained close to 19.5%, even as the top tax bracket was brought down from 91% to the present 35%. This is what scientists call an "independence theorem," and it cuts the Gordian Knot of tax policy debate.

The data show that the tax yield has been independent of marginal tax rates over this period, but tax revenue is directly proportional to GDP. So if we want to increase tax revenue, we need to increase GDP.