When a start-up company goes public, it gives the original shareolders a chance to sell their shaes to the public market.  the original shareholders don't have to wait for dividends, they can just cash out.  With young companies going public, it would be incredibly rare (I can't think of an example) for the company to pay a dividend.  Normally they need the money to reinvest into the company to grow, and in fact may need more than they can generate themselves, and thus need to put a secondary offering out to the public to get more money.

anyway, my apologies if we are miscommunicating on these issues.