Ticket scalpers, too bad.
How about the concessions company, peanut, ice cream, water, soda, hot dog hawkers. These guys work for tips.
If 30,000 people buy one $9.00 beer = $270,000 in just beer sales. LOST by the venders.
I forgot about the lost revenue in parking. Up here in Boston it costs $20-30 to park near Fenway during a game. If 10,000(a conservative estimate)automobiles needed to park around Camden yards today, that is another $200,000 or more in lost revenue.