A common misconception held by some is that the stock market is a zero-sum game. It isnt, since investors may bid share prices up or down depending on numerous factors such as the economic outlook, profit forecasts and valuations, without a single share changing hands. Ultimately, the stock market is inextricably linked to the real economy, and both are powerful tools of wealth creation rather than zero-sum games.
http://www.investopedia.com/terms/z/zero-sumgame.asp