You make a lot of good points. I think we should also consider the fact that if you invest your money rather than spend it, the firm may not invest directly into capital projects for increased productivity. So much money is returned to shareholders via buybacks and dividends these days. So in those cases, your wealth isn't transferred to labor, instead it's transferred to other shareholders who already have wealth and a flywheel effect occurs. This creates more and more distance between labor and capital.
I could be completely off here but am interested in opinions on this.
You're not wrong that that effect can exist. And I'm not saying that investing is a totally altruistic, virtuous action. However, the criticisms of the stock market as not being "real investing" are largely off-base. Liquidity encourages investment -- illiquid investments are universally less preferred than liquid investments, all other things being equal. Even if non-IPO investors/subsequent issuance investors are not directly providing capital to a company, nobody would participate in IPOs or other stock issuances unless they were confident of a market for that stock in the future. Therefore participation in the secondary market for stocks is necessary for a primary market to exist in any meaningful way. (In a similar way, if the public market did not exist, there would be much less private investment, much fewer startups, etc.)
I could be completely off here but am interested in opinions on this.