How do we explain a government regulatory agency gone wild, turning viciously on its subject and seeking to destroy or impair it, regardless of the harm done to the general public?

Some tough-minded economists some years ago developed a realistic description of political behavior called "public choice theory."  Under this view, everyone in the political process -- voters, politicians, bureaucrats, lobbyists, and the special interest groups who hire those lobbyists -- are motivated primarily by self-interest.

However, the theory continues, the degree of interest varies, and so the amount of knowledge about the process varies.  For example, if a $300-million bridge to nowhere is proposed as an earmarked provision to a defense spending bill, the average taxpayer stands to lose only a few dollars, while the building contractor stands to gain millions of dollars.  So the contractor will follow closely the progress of the pork-barrel spending as it works its way through Congress, while the taxpayer will not.  Economists say of the taxpayers that they are "rationally ignorant" -- since they stand to lose only a few dollars, it is more rational for them to focus on their daily lives, where they have more to lose.