Winning is not success. Losing is not failure.

An intrinsic (some would say neccessary) aspect of all competitive sport is that there are winners and losers. Everyone likes to be a winner, nobody likes to be the looser, but everyone is at some point. Loosing sucks, loosing hurts. Despite our common experiences reactions to winning and loosing are far from uniform and in fact how we react to a victory or defeat is more important than the actual victory or defeat itself.

In individual competitions (such as chess) when you loose a match there is nowhere else to look for (or attribute) the cause of your defeat. While winning or loosing a particular chess match has no bearing on future success in any aspect of your life (or even future your chess success) how an individual chooses to interpret victories or defeats, will according to sport and industrial psychologists have a bearing on future success in both life and sport.

For some a negative emotional reaction to a defeat is a sign of 'hunger' or strong motivation to win, but this same behavior can also -simultaneously- indicate a reaction to a percieved threat to self esteem(fear of failure), which can manifest itself in negative even counter productive ways.

It is an important aspect of any sports coaching to help a competitor with the correct and positive interpretation of any victory or defeat (often called attribution psychology). It is arguably even more important in intellectually intense competitions such as chess, when active brains meander towards post mortems in unpredicable ways which can loose sight of the bigger picture.

Studies have consistently shown in a variety of fields ranging from professional sport, entreprenuership and even academic attainment, that a defining characteristic in long term success is the ability to percieve wins and losses as merely "learning experiences". The correct attitude to both helps construct and maintain a balanced and healthy mental framework (some call it an emotional intelligence) in the face of those occasional knocks that challenge us all from time to time.

References
Attribution psychology in sport
EI in sport coaching
The right attitude in chess

"A merry heart doeth good like medicine." --Proverbs 17:22

"The price of success is hard work, dedication to the job at hand, and the determination that whether we win or lose, we have applied the best of ourselves to the task."
Vince Lombardi, American football coach