Neal Gabler, a favorite, for the New York Times:

People run for the presidency for all sorts of reasons. But Donald J. Trump may be the first to run because he sees a presidential campaign as the best way to attract attention to himself. There seems to be no other driving passion in him, certainly not the passion to govern.

Clearly.

Attention has always been the foundation of Mr. Trump’s modus operandi. Basically, he sells his name: Trump steaks, Trump water, Trump University. You have to hand it to him, though. He discovered that, in a celebrity society like ours, where so many people are competing for attention, running for president puts you a leg up even on the Kardashians.

How do we keep this from happening again?