[URSpider94]

This is definitely not true. In a zero-sum game, every bit of profit one person makes comes from the pocket of the counterparty. A stock option is a zero-sum proposition: at the expiration of the option, one party ends up “in the money”, the other party is “out of the money” by the same amount.

Stocks are not a zero-sum game. They have sustained value, so when I sell you a share of stock, you get the share, and I get money equal to the value of the stock.

One might argue that day trading is roughly a zero-sum game, if we make the simplifying but inaccurate assumption that the values of stocks don’t change across a trading session, and assuming that everyone goes home each night with all positions closed out.