If I buy a stock from you, my money goes in to the market and yours comes out in an equal amount, so you are right in that regard.
I think we can safely define stock market winners, in general terms, as those who are able to sell their stock for more than they bought it, while the opposite would be true of the losers.
Just because I sold my XYZ at $100 and it went to $50 doesn’t make me a winner, though. You could be judged a loser because the value of your position fell. That’s pretty clear. Would you call me the winner if I had bought XYZ at $110, though? I won’t make a single penny off the fact that the stock you bought from me fell in value.
You see what I mean. Trading stocks is a simple transfer of assets. Once the seller of the asset has sold, he can no longer recieve any economic or accounting benefit (or loss) from it.
This leads me to another question. Are bull markets dependant on a flow of fresh capital to keep peaking?
Essentially yes. Any bull market (stock or otherwise) requires continued demand from buyers (excess of supply from sellers) to keep prices going higher. Because leverage ratios are lower in stocks it takes more absolute capital inflow to drive stocks higher than would be the case for other markets where more leverage is used. Leverage creates buying power.
I have always thought of the stock market as a market that reflects what people are willing to pay for an asset, but not a market which by itself generates “real” wealth by the increase of asset prices.
All markets reflect what people are willing to pay for things. That is their reason for existing. When you are talking about actual assets (and not just agreements to exchange assets) then changes in their price has a direct impact on the wealth of the holder. Stocks are no different from property, a bar of gold, a barrel of oil, an antique car, baseball cards, or any other asset.