Tyler Cowen asks why do people lose originality as they gain influence? There are two observationally equivalent ways to explain it.

  1. Since nobody really knows anything more than anybody else, opinion-rendering boils down to a game where everybody makes a random guess.  The outcome of this game is that one person says something unconventional that turns out to be right.  (by pure luck.)  He gets noticed for that.  Influence is the reward for being noticed.  (We don’t have to assume that the public is unaware that he is just as ignorant as everyone else.  The public is just trying to coordinate on whom to listen to.  Winning the random-guessing game makes him a focal point.)  Having influence is nice and in order not to jeopardize that he goes on saying the same thing as before which turned out to be right and is now conventional wisdom.
  2. Since nobody really knows anything more than anybody else, opinion-rendering boils down to a game where everybody makes a random guess.  And people go on making random guesses over and over.  People whose guesses are right get noticed and get influence, the more unconventional the guess the more you get noticed. Its very rare that something really unconventional is correct, so the people who repeatedly make unconventional guesses eventually lose influence.  It follows that those that survive this game for a long time are those whose random guesses were unconventional once and conventional the remainder of the time.  We forget about all of the others.

Tyler asked for case studies.  But given the nature of the question what he really wants is a theory that generates a forecast that we can test against future data.  So as you guessed from the title, my case study is Noriel Roubini.  In 10 years he will either continue to be a regular talking head who no longer says anything unconventional (theory 1) or he will continue to make unconventional guesses and will have lost influence and be forgotten (theory 2).