It's awful—it ignites all those raw, instinctual emotions that managed to survive man's transformation from fearsome hunter-gatherers to mobile-phone perusing drinkers of lattes.
Losing means someone else is better than you. That despite your best effort and innate talents, you failed. Losing unites aspects of our humanity that otherwise seem completely unrelated.
Like teenage crushes and SEC football—getting dumped for some other chump feels a lot like watching your team get stomped by their hated rival.
Despite this fact, we expect people to take their medicine and respect the result.
Nobody likes a sore loser in sports because it ruins one of the greatest and fun elements of playing or just being a fan—being on the winning side.
Being a sore loser craps on the winner's moment in the sun—and that moment is precious because that winner was undoubtedly a loser at some point. And if you elevate it to the professional level, then the expectations for decorum and respect are even higher.
Yet, losing stinks.
There will always be people who succumb to the white hot fury of being the loser—some more than others. When some of the biggest and/or most well-respected names are proceeded by "sore loser," it usually makes headlines.