The roofing company example is a good one. However, the conclusions are not correct. I own a small company and just sold stock (paper?) in my company to several rich guys. Here is how it works. First 100% of their investment goes to growing the company - if I sell something only the profit portion goes to fund growth.

In the roofing example, that investment allows the roofing company to expand into siding and hire more people. In addition to the siding workers, he hires another office person to answer the phone, send out bills and generally keep track of things.

Even for a publically traded company, when you buy stock, some of that stock is being sold by the company to raise money for operations and growth. If it was just people trading money, companies would not care so much about stock price.