Who cares?
If Trump thinks he won by a landslide even though he didn't, maybe he thinks other false things as well. Like flag burners don't have constitutional right of free speech, like Ted Cruz's dad met with Lee Harvey Oswald the day before JFK was shot, like thousands of Muslims celebrated on rooftops of New Jersey on 911, like 2 million illegal votes were cast for Hillary, etc. etc. The capacity for self-deception is not a quality you want in a President of the United States.
I know, I know, Obama this, Hillary that.