mostly they do it as a entertainment or to have fun,some play it professionally and for betting and earning,this is my suggestion,also i got few froms searches,
Chess Game is a Great Solution!
While playing chess you have to think constantly. You solve hard mental tasks over and over again. A time limitation forces your brain to work even harder!
This training improves your mental skills, your thinking process.
This will bear positive influence on your life in general!
Physical exercises improve your body.
Mental exercises improve your brain.
Since we are “homo sapience”, a brain activity should be more important for us

Chess Improves Your Psychological Skills.
This is the 2nd important argument for playing chess.
Chess game/tournament creates highly competitive situation for you. You need to have a strong character in such circumstances.
"I developed my strong character by using chess."
A.Alekhine.
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Chess gives you a constant and objective feedback (your results, rating, your final standing in a tournament). It shows you clearly your psychological (mental) weaknesses. Therefore this gives you great possibilities for self-improvement (as a chess player, and as a personality).
In my new course I explained some important principles of human brain work. You will know how to digest new information easily and how to get new useful skills. Also you will know how to do it in the most efficient way!
By using this knowledge you will speed up your chess progress and will enjoy greater results.
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Regards,
GM Igor Smirnov