Picture history of Trump’s hair through the decades: http://www.huffingtonpost.com/entry/donald-trump-hair-evolution_us_576025e9e4b0e4fe5143c597
I think the best explanation is that he had flap surgery, made to appear even worse because of having bad taste in hair styling (does he really need to swoop his hair so low across his forehead?).
And can’t he get some kind of surgical correction? Or does he really think he looks human?