How does an understanding of the brain explain why people experience strong emotional responses to major sporting events? Anyone know studies or theories that explain how massive competition events between countries or parties, like the Soccer World Cup Tournament finals or Olympic Games affect our brains?
Why do people suffer so much over these events?

I want to understand the fact that people get so excited or so depressed about that events that have no real impact in their lives. Seeing people cry because their teams lose is incredible, and I think that these reactions are unconscious and must have an explanation involving how these events affect out brains.
This is only a partial answer (since the question scope is so large) but it is one of my favorite empirical findings. 

It turns out that simply watching your favorite team win or lose has physiological impacts. Specifically, if a team you are rooting for wins, your testosterone levels will increase, and they will decrease if your team loses. This was demonstrated by Bernhardt, Dabbs Jr., Fielden, &amp; Lutter (1998). In two experiments, they measured testosterone levels in male sports fans before and after watching their team win or lose. In both experiments, people who were rooting for the winning team showed an increase in testosterone relative to their testosterone level before the match, while people who were rooting for the losing team showed a corresponding decrease in testosterone.

This doesn't explain why we get so invested in sports, but it might help us understand some of the extreme reactions that sports fans have after a particularly exciting match.