Everyone loves a dark horse. It's just human nature.
People can hardly contain themselves when a heavyweight boxer everyone expected to get the snot beat out of knocks out the supposedly invincible Mike Tyson. They applaud when an 18-point-underdog New York Jets team knocks off the mighty Baltimore Colts in Super Bowl III. They revel when a 1000-1 long-shot U.S. men's hockey team stuns the juggernaut that was the USSR in the 1980 Winter Olympics.
Of course, some of those people were cheering because by placing a wager on those long shots, they came away with a fat bag of cash.