Donald Trump is justifiably proud of securing his win on a very low budget. He got top billing in the news for much of the campaign season due to his masterful manipulation of the mainstream media. As a consequence, he did not have to spend much money to get his message out.
A lot of the money that the Trump campaign spent was to pay for services provided by the Trump empire: the campaign paid him for the use of his plane, for renting office space in his buildings, etc.
In the last week before the election Trump announced that he would chip in $10 million of his personal money to his campaign, but it is not clear whether he ever did that and whether it was a contribution or a loan.
Someday, someone will run the numbers, but there is a good chance that after the loans are paid back and the amount earned by Trump’s companies is added up, it will turn out that Trump ended up earning more money from the campaign than he personally spent on it.