> The world is finite. Resources are finite, and infinite expansion is impossible.
If you were right, the $10 trillion China added to its economy annually (you know, just ~$64 trillion of new GDP that didn't exist before, over the next five years) - in just the span of ~16 years, would have had to come out of someone else's pocket, which would have caused extreme collapse in numerous other major economies to make room for it. That of course didn't happen at all, the rest of the globe's GDP expanded along with China in real terms.
For all realistic practical purposes - since we're nowhere near maximum resource utilization - that has yet to be an actual problem and we're up to 7.x billion people now. Every serious problem to that expansion, we've managed to solve, enabling continued expansion (see: we were all supposed to starve to death decades ago).
Back in reality - and out of the realm of theory that only exists in a strict vacuum - Capitalism is the exact opposite of a zero sum game. That has been proven by the radical improvement in living standards at the median for all the developed nations, all of which heavily utilize the free market economic system (including all of the Scandinavian nations, none of which are actually Socialist at all).
If Capitalism were a zero sum game, China would not have just enjoyed the greatest, fastest mass standard of living improvement in world history thanks to its modest adoption of the free market, and its blatant shift away from Statism.
The free market largely won globally, and thanks to that, the world has less poverty, war, violence and starvation than at any other time in history.