Where did that assumption come from? Just because people disagree doesn't mean they are bought off. Citation definitetly needed to even remotely approach a pattern like "bought off" let alone a proof.
It comes from years of observation and study of the structure of the government and society. If you're interested there are many books about this from Manufacturing Consent by Edward S. Herman to critiques of the academy that shut up after the state started funding them extravegantly after WW2, to the current ossification that is easily observed where no policies are allowed to shift that benefit the wealthy at the expense of society. It is so extensive that one or two citations isn't sufficient and deserves a lifetime of study.
