Gambling, is the creation of risk. It is an enterprise undertaken or attempted with a risk of loss and a chance of profit or success. The voluntary risking of a sum of money on the outcome of a game or other event. 
Gamblers take risky action in the hope of a desired gain. Gambling is taking risks that have no economic utility. Activities like trading in Futures, which provide market liquidity, or owning scarce assets short term, may be speculation but it is not gambling as investors use the term. Because someone has to take these risks. Gambling, creates risk where there was no risk before.
1590s "to play, jest, be merry, to play, to play games. 1726 (implied in gambling), 
Sumflow 19:38, November 1, 2010 (PDT)