Trump wanted to be a NFL owner
Most, if not all of its owners, are Trump supporters.
But could not get a team
https://edition.cnn.com/2017/09/25/opinions/trump-tweets-revenge-on-nfl-pearlman
In the 1980s, he owned a team in the competitor USFL.
That league was moderately successful. They had future Hall of Fame talent like Reggie White and Steve Young.
Trump and some other owners changed their schedule to the fall to compete directly to the NFL
Some felt this was a move to force a merger of USFL to NFL.
This did not work so the USFL ceased operations.
The USFL sued the NFL for antitrust but were only granted $3 in effective damages.
Beginning with the trials opening day, Rothman asked himself a single question: Who is my bad guy? He sought someone the jury would find difficult to believe and even harder to like. He sought someone with false bravado, with arrogance, with indifference. He didnt want the jury to think about a sad little league going up against a powerful machine. No, he wanted the jury to see that the USFL, sympathy be damned, was its own Frankenstein. The more I developed the strategy, he said, the more I wanted Donald Trump as my fall guy. I would call it Donald versus Goliath.
https://www.theguardian.com/sport/2018/sep/11/the-day-donald-trumps-narcissism-killed-the-usfl