“It’s a zero-sum game, because there are always winners and losers in the stock market.” Is this true, outside of options? Most people are long and the stock market has always been on an uptrend.
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.