Hopefully you have watched some games and cheered for a team with rabid, blind, devotion. While understanding the way the game is played will help you appreciate a football game, it still does not explain why 250 lb. Essentially, that is what I intend to begin to explain. First of all there is the hero factor. Football's very nature produces heroes from every position and every stage of the game.
Every play comes down to a battle between individuals working in the confines of a team.
Every snap triggers a battle of wills and strength on the line of scrimmage. Every running play challenges the other team to stop this individual carrying the ball. Every pass has the potential to be picked off. In each case, one man can step up, defy the opposition, and win the battle on his own. The lineman can sack the opposing QB for a major defensive stand.