The quote you referenced talks about money not wealth. They are not interchangable. In fact this quote actually refutes your position since it says that wealth does change with stock market price changes.
No, net wealth does not change. Read it again. That is the net wealth of both parties, not one party.
"Their aggregate financial wealth may be higher or lower, but the total amount of money they own remains unchanged."
Correct. Aggregate financial wealth can be higher or lower as a function of debt and credit markets. Read your own links for the answers. Once you remove debt from the equation they net out to zero.
I don't think this is true. What happens when a stock gaps down big and never looks back? Doesn't the total amount of money just got LESS between yesterday's close and today's open???? By the way the site itself has some serious missconceptions.... The stockmarket is not a zero sum game because (beside commisions) a relative small amount of stocks changing hands can determine the value of the rest...
Please do not use the word money when you mean wealth. They are not the same at all! Don't go there...(again)
No, everyone that bought at higher prices paid that money to the sellers. Those that were long, lost their money to those that sold. If these don't net out to zero, somebody cheated somebody somewhere.
What happens when MSFT gaps down $1 overnight without any trades occuring. If I have 1000 shares I just lost $1000 of wealth. Now who is the counterparty that increased their wealth by $1000?