Take Not Thine Ownself Too Damned Seriously
. . . the 11th Commandment
The current occupant of the oval office clearly is afflicted with a surfeit of unearned and undeserved self esteem.
Deep down, he probably recognizes the reality that his ego will not permit him to face -- that he is devoid of any accomplishments, experience, or talent qualifying him for the office that he holds. He masks his inadequacy with constant self-aggrandizing statements and claims (including those in which he tries to equate his tenure with those of successful past presidents). Such use of his rhetorical skills rules out any possibility of genuine self-deprecating quips or humor.
This requires the little o to always act earnestly as the BIG O. It explains why his rare efforts at humor always fall flat, why he he always seeks to belittles anyone who criticizes or disagrees with him, and why he always lashes out against, and irrationally disparages any and all expressions of critical and dissenting views.