The Joy Luck Club begins because of a former club that Suyan was part of that forms part of the rich mythological heritage that her daughter is brought up with and is told to the reader in the first chapter. The original Joy Luck Club was conceived of as an idea to cheer up the women involved and to allow them to extract joy and pleasure out of a time of great stress and worry, when the Japanese were invading. The Joy Luck Club allowed the women to focus on the positives and also to try and deal with their pain and loss. Note what Suyan says about it:

It's not that we had no heart or eyes for pain. We were all afraid. We all had our miseries. But to despair was to wish for something already lost. Or to prolong what was already unbearable... What was worse, we asked among ourselves, to sit and wait for our own deaths with proper sombre faces? Or to chose our own happiness?

The hope of luck at the game of mahjong was the women's only joy, and so the Joy Luck Club was a tradition started by Suyan in China as a deliberate choice to focus on what was good and try and deal with both the past and present pain and stress. This of course is exactly the same reason for the resurrection of the Joy Luck Club in America, as although there is no war going on, the four women involved have all gone through traumatic leave takings from their homeland and find themselves in a country that they do not understand.