Sometimes an old athlete may want to come back for some special match. Some bettors might still bet on him despite of old age and lack of recent experiences in the sport. That is because of what we call nostalgia. They might recall the past memories or past performances of the athlete that may not necessarily reflect the recent performance of the athlete. So be careful when betting because you might just be nostalgic.
I remember when Manny Pacquiao came back to fight someone, I can't remember the opponent's name after many years of hanging his gloves. Many people believed that he was going to win based on experience while some others believed that the younger opponent was going to win based on his age and speed. Manny lost that match and to people who bet on him, they also lost their monies. This is a typical example.
That is the best example of when emotions trump reason. For pretty much any sport youth trumps experience as soon as the difference becomes a lot. I know of people who bet on such matches and they often lose money. Sometimes the judges score favorably to not be too harsh on the legends but even that is wrong.