Just looking at Saints tickets, 72,000 at say an average price of $150/ticket = 10,800,00/game! Say an average of $100 per fan spent on food and drinks, that is another 7,200,000/game. A total of 18M per game x 9 games (combining the two preseason games). That is a total of 162M for the season; conservatively. I am not counting parking or merchandise. Multiply 162M x 32 = 5.2B.
The 5.5B is conservative IMO.