I started 2016 covering Jeb Bush — the man with the $100 million war chest, the famous last name, the family connections, the stellar conservative résumé and the serious policy proposals. And I watched him hobbled by one single insult, just two devastating words: “low energy.” When voters started repeating Mr. Trump’s insult back to me, without quite realizing they were parroting him, that’s when I knew. — Ashley Parker