It's possible they weren't as much upset at losing as they thought they could have done X thing better than they did. I would be pretty angry at myself if I got all the way to the Olympics and my performance didn't meet my own personal standards. Perhaps not, but it could apply to some anyway.
During every event, especially where athletes are crowded together, there are a few people who fall down, destroying any chance they had of winning. I just want to hug them. That must be an awful feeling.