Originally shareholders received a part share in the total profitability of the company. A dividend was the main source of income from investing.

It didn't take them long to figure out that buying and selling shares of a company to other investors was usually more profitable than dividends. Its a hell of a lot easier to lie about potential value of the company than it's current reality.

So for the past 100+ years the market value of the shares are often separated from the reality of the company. The value of the shares only exists because people or automated programs are willing to pay the amount. This is how companies who are operating under a huge deficits have increasing stock prices.

Since the value of the shares can be so easily manipulated, market manipulation is the normal way investors make money today. It also means that major stockholders don't give a fuck about long term value of the company, the employees, or the damage to society & the environment they cause. They only care about making quickest profits, then passing the dumpster fire they created onto somebody else.