> it's a negative-sum game
This is a misconception often touted by those who think they know something.
The other side of a trade doesn't necessarily win/lose if they needed to exchange $xxxm to open a factory on another continent. Not all market activity is speculation/investment. Much of it, some say the majority, is random business activity. This skews the game theory analogy enough to make it invalid. There is enough inefficiency, noise and long term trending for a non-naive participant to profit from speculation. For now.
Kudos on the word gimcrackery.