I would support that guy in a heart beat. Not only do you have to pay 8 dollars for a beer but you have to pay like 10 bucks for a hamburger at the Bears game and the food at Soldier Field is the worst in the nation and I've been to over 20 - 30 sports stadiums from Yankee Stadium to Safeco Field in Seattle.
If you are planning on going to a Bears game make sure you eat before hand.
The high prices for food and drinks, at sporting events, aren’t mainly because of taxes. The main reason is because the vendors are greedy, although taxes increase the prices, slightly.