Wag, look at the data:
http://reason.com/blog/2010/11/29/the-remarkably-stable-amount-o
You are forgetting that payroll tax ends at a relatively low level of income (I mean relative to the poeple who pay most of the taxes, the top percentile people) so that in terms of total federal revenues the payroll tax is relatively trifling (though of course not for the people who pay it).
Try again, Wag.