All this juvenile behavior has caused Trump to slump in polls. Fox News found that after the first debate, 67 percent of likely voters said Hillary Clinton had the temperament to serve as president. Trump’s temperament number fell a point to 37 percent — a 30-point gap.

Why is Trump having such difficulty changing his behavior when he should know he is hurting himself? He has provided the answer. Last year, financial journalist Michael D’Antonio published Never Enough: Donald Trump and the Pursuit of Success. The book was bolstered by ten hours of exclusive interviews with the mogul.

Some of the quotes are very revealing. When asked if he is ever introspective, Trump replied, “I don’t like to analyze myself, because I might not like what I see.” When queried about his temperament, Trump said: “When I look at myself in the first grade and I look at myself now, I’m basically the same. The temperament is not that different.” He said he “loved to fight” as a child, “any kind of fight, loved it, including physical.”

Well, assuming Trump is telling the truth, there’s the answer. As a grade-schooler Trump threw cake around a birthday party and gave a teacher a black eye because he was ignorant. His behavior was so out of control that his parents exiled him upstate to a military academy. His experience there only cemented his bully-boy traits. Trump has described the students and the drill sergeants there as people who would “smack the hell out of you.”