yes clearly the stock market is not zero sum for the simple reason that the seller may be simply trying to raise money for their business on the IPO, and if the stock keeps going up the all are winners. sellers are not always traders, and why can't that be for futures? let's say that hedging risk produces efficiency, so selling in a rising corn market can be good if you are a producer. sure you may have sold at a higher price but hedging allows you to plan.