The last 42+ weeks of business school has taught me many things. If there is one thing that I can articulate in my learning is that business success is about balance. One one hand, you have your customers who are paying you some money for the benefits that you are providing through your business. On the other, you have your shareholders (even yourself) who are trying to ensure that your business generates enough money to justify investment.
A successful business is one that delivers the best set of benefits for its customer, while ensuring that it is able to retain most of the money that the customer provides for satiation.
In simple terms, business success is nothing but revenue / incremental costs.
Jonathan Knowles, who spoke during the New York brand management winterim in winter 2009/2010 was the one who drove home this nugget of awesomeness. I highly recommend reading his book, Vulcans, Earthlings and Marketing ROI: Getting Finance, Marketing and Advertising onto the Same Planet [Amazon Associates link]. Wonderful read.