That's because the stock market is not a closed system. Number of shares, number of players, and other factors are not fixed.

So. The exchange of a share of stock at any moment in time is an exchange of one equivalent piece of equity for another. No money is lost in the process. The value of that share of stock depends on the moment in time the transaction is made, and if no transaction is made, no money is gained nor lost.

So if there are ten initial total players in the market, for a defined period of time, each of these ten players initiate a fair exchange of equity. They give up some equity for another piece of equity of equal value. The process of exchanging equity may or may not create a perceived demand that at some later point in time raise the perceived value of the stock.

1) If any of the initial ten players chooses to obtain additional stock that is now worth more, then they will have to give up more equity in order to obtain an equivalent amount. If they do so, no equity is lost in the process if they obtain the same share of stock in exchange for a larger amount of equity or money. Previously purchased shares are not de-valued. If the players sell to each other, or to new players no money is lost. It is possible using this case, and variations of, to continue to increase all the shareholder's equity over time.

The opposite is true, it is possible for money to exit the system entirely, and equity to completely dissapear, as in a case of bankruptcy. You can exchange a large amount of equity for some number of shares that due to any number of reasons could suddenly be worth zero.

In a zero sum game, if 1 person loses a dollar, another person gains 1 dollar. In the stock market, being not a closed system, 1 person can gain a dollar, exchange the property to another person, who will gain another dollar. Also, 1 person may lose a dollar, and another person can lose a dollar as well. There's no rule that says everything sums to 0.

Calvin