Earlier quoted context omitted.
The stock market is not a zero sum game. I don't know where people get this idea that because every transaction involves two sides, the sum is therefore zero. Every transaction in the "real economy" also has two sides, and we all know that grows. The stock market grows too. There are even indexes to track how well it is growing.
The “real economy” runs on a fiat (inflating) currency system that is effectively not zero sum. The stock market is a closed system that currencies feed into - at the end of the day it’s still a measure of a fixed amount of value and thus zero sum.
This is why fiat currencies are so useful: you can change the length of the "ruler" to accommodate changes in the thing you're measuring, so the value of the increment remains stable.