The most commonly mentioned one is "to make money". Increasing wealth for the stakeholders is the driving force.
Opposed to this view is the one that posits that business leaders need a sense of being called upon to seek the common good, to make a difference, to make the world a better place for their having been there.
This wider view shares benefits across society rather than the benefits going to a small elite of shareholders and owners.
It is very encouraging to see billionaires like Bill Gates and Warren Buffett using considerable amounts of their substantial fortunes to reach out and help others. This is ethical business behavior that should be applauded.