It, along with the whole "smiley buffoon" act is an affectation the embodiment of Oxbridge arrogance and callousness adopted to make him appear silly in an endearing way so that his actual words and actions would appear less villainous than they actually are.

I'm going with unaddressed mental illness run amok, leading to apathy regarding presentation, hygiene, etc. Also why Trump looks and smells like literal shit.

He’s slowly going the idiot version of super-saiyen.

This isn’t even my final form!