The first 4  reasons...

 This game is a sport. It is universal, formative, educational.

• It is universal, played everywhere, at all ages and between all ages. It is a common bond.                                                    
• It is formative.  Numerous studies show that regular Chess practice significantly improves academic performance, develops skills such as imagination, observation, attention, concentration, memorization, anticipation, deduction, Determination, thoughtful risk taking .. 
•  It is educational because it facilitates socialization, respect  others, respect rules, tolerance and provides essential peaceful weapons to grow in progress.

 ... a 5 th reason...

In chess,
Age, physical, sex, social origin, skin color
Are not important.

Grandson can give a lesson to Papy.
The dwarf can only make one mouthful of the giant.
Betty Boop forces Mr. Matcho to give up the game.
Gavroche imposed himself on Louis XIV.
...................... the reverse is possible .......................

... and  so many others