But in the example it doesn’t sum to zero. The stock is growing by 10 dollars a year. Person A Purchases the stock for 10. It is now worth 20. Subtract out the transaction and that leaves 10 of generated wealth. Person A sells to person B for the 20. They bring 20 to the system, which is worth 20. At this point, the transactions sum to zero. However, a year later the stock is worth 30. Transactions 20, value 30, 10 of wealth generated.
In your example, you are closing the game after person z purchases. You are making it more a game of Hot Potato(e). The stock market has been around longer than I have been alive, and will likely continue to be there long after I die. It is dependent on new people entering because when I die, my kids might not want the stock, so they sell it. Your kids might want it, so they buy it. The stock market will still be there.
Yes.
In a ponzi scheme, each person is paying money up-stream, but not getting any value for the purchase. It is inherent in the game that someone will eventually lose money. It is not inherent to the stock market. It does happen. Someone might have an incorrect perception of the value of a company. or there could be fraud (Enron). But it is not part of the nature of the stock market.
Again, i think your confusion is based on how the price of stock is determined. If,for example, you have 100 shars of stock, each share should represent a value of 1% of the company. Say their assets = 100, then each share should be $1. Simple right? But you also have to factor in the companies reputation, future profits, supply and demand. Say after all these things, everyone thinks the stock is worth $2, and that is what it sells for.
Keep in mind that these are bery simplistic answers. I hope I am not causing more confusion.