Late last week, Sen. Jim DeMint, R-S.C., announced he was leaving the Senate to become president of The Heritage Foundation, the country’s most influential conservative think tank. From his new office perch just five minutes from the Senate floor, DeMint, a tea party gladiator, will enjoy unrestricted power to pursue America’s ideological renewal at six times his Senate salary. Members of Congress cashing in on their experience is nothing new. But it would be wrong and simplistic to assume DeMint is trading his institutional power as a senator for money and ideological purity.