Sam Walton's employees would not be able to generate that fortune on their own. You seem to underestimate the role of leadership, vision and other business skills in creating a company. Not to mention that many of those employees probably also made their own small fortunes along the way.
Also, you make it sound like Sam Walton somehow has a debt of gratitude to a society for it allowing him to get rich. I think that no such debt ever exists: in exchange for those billions of dollars Walton made society has already gotten something equally valuable in return, i.e. Wal-Mart mall in every city, providing cheap and easy access to all kinds of consumer goods. That's how business works: making money by providing services that society finds valuable.
The fact that leadership is necessary (which I do not deny) does not imply that some particular share of the resulting surplus value should go to said leadership. The share of surplus value captured by capital is something we get to decide as a society, and the idea that "as much as capital can manage to capture" is a natural and just share is a pervasive and pernicious lie.
But of course it implies exactly that. People should be rewarded for their skills and their contribution to the success of the company, which means that lion's share of profits goes to those on top. And no, we as a society don't get to decide that, because companies are privately owned by individuals, not by society as whole. Why should society decide how should I spend my money?
Yes, reward them for their skills and work - not what they can capture of someone else’s hard work. It is an article of faith in some quarters that someone who manages to put themselves in a position where they can skim the labor from employees or renters somehow means they are a wealth creator. Usually though, these “wealth creators” are just capturing wealth generated by someone else.
Also, you make it sound like Sam Walton somehow has a debt of gratitude to a society for it allowing him to get rich. I think that no such debt ever exists: in exchange for those billions of dollars Walton made society has already gotten something equally valuable in return, i.e. Wal-Mart mall in every city, providing cheap and easy access to all kinds of consumer goods. That's how business works: making money by providing services that society finds valuable.