> "In fact, if anyone earns over 10%, that means that someone else must be earning less than 10%. So, maybe it's a 10-sum game, but most people still use the term "zero-sum game" to describe the situation."

You fixed the rate of increase. Jesus. Obviously it'll look zero-sum under those circumstances. The point is, the more efficiently the stock market's played, the faster it grows overall (in theory). It's not zero-sum.