I think you have to differentiate between income stocks and growth stocks. Income stocks pay regular dividends and the stock price stays pretty flat. So you might get a 10% yearly return on your investment in that company.

Growth stocks invest most or all of the profits back into the company. So you won't get regular dividends but the size of the company will increase rapidly, and the value of your shares will too.

I see what you're saying though about what tangible value does one single share have if it doesn't pay dividends. But if it had no value then that means a big shot could buy a really profitable company for really cheap. Then he could collect the profits or re-invest the profits or whatever. Either way, the profits are his. And even if you own 1/1000th of a company, then 1/1000th of the profits belong to you. You only get 1/1000th of a say in whether those profits are cashed out or re-invested for bigger profits later on.