I think this topic has become popular at least in part because the U.S. President has been diagnosed (not by his going to a psychiatrist) as having narcissistic personality disorder.

I personally have found some of the articles on the subject to be helpful and interesting, since my mother is narcissistic.

They also help explain what the POTUS says and does--and should be a good predictor of future behavior. Alas.

I'm sure this topic will lessen in popularity with time.