QUOTE (Dam8610 @ Nov 30, 2016 -> 05:00 PM)
Simple economics. Say a person, let's call him "Soxtalk poster Deadpool", spends $250 on something Cubs related (gear, tickets to a game, concessions at the game, a ride down the urinal trough at Wrigley, whatever). Now "Soxtalk poster Deadpool" does not have that $250 anymore, and cannot spend it on White Sox related things. The Cubs existence took the possibility of the White Sox getting "Soxtalk poster Deadpool"'s $250. They may not have gotten it anyway, but now there's a 0% chance instead of a >0% chance.