Donald Trump has many comically over-the-top personality traits. One of them is his obsession with credit. He either attempts to take credit for things he didn't do or complains that no one is giving him credit for something he did do.
He claims to have come up with the word "fake." He took responsibility for a decades-long trend in aviation safety, "Since taking office I have been very strict on Commercial Aviation."
He even went so far as to claim that people in America are saying the phrase "Merry Christmas" only "because of our campaign."