Why act against economic self-interest?

I've been puzzled for some time now about the appeal that the Republican platform of low taxes has for the lower middle class. The line that "you know how to spend your money better than the government" really resonates.

But there's a disconnect between people who want the streets paved, and lots of services, these are not Libertarians on the whole, and the notion that they aren't getting their money's worth.

Yes, government will always be inefficient. But it will be just as inefficient with less money, it will simply do less for you. The incremental cost of popular government services is cheap for people making $50,000 a year, because more of those costs are borne by people higher up the economic ladder.

I've been particularly impressed by the analysis by Alan S. Blinder in the New York Times about the economics of Republican vs. Democratic administration.
http://www.nytimes.com/2008/08/31/business/31view.html?_r=1&em&oref=slogin

It makes sense to me. When we don't invest in unsexy things like infrastructure, the economy doesn't grow as fast. It's insidious because it's easy to measure taxes, which you pay, and not so easy to estimate the monetary benefits of government programs, which are complex.