You don't acquire a $100 million fortune by performing 1000x the labor of a person with $100k, you get it by skimming the fruits of a lot of other people's labor.
Or you can solve some previously unsolved problems which allow you to produce better products for lower costs than your competitors. This is how Carnegie, Rockefeller, Walton, Bernard Kroger, Aaron Montgomery Ward, Richard Warren Sears, etc. all made their fortunes. Even modern tycoons like Jeff Bezos, Elon Musk, Bill Gates, etc.
Can they get too much market power and start stealing from society? Absolutely, that's why we have anti-trust laws. But to see a fortune and assume a theft is to fundamentally misunderstand economics.
How much value? Who determines how much you get to keep of it? These are highly charged political questions that have driven a lot of economic history!
> But to see a fortune and assume a theft...
I never said theft. I responded directly to the idea that people vast wealth is merely "the fruits of one's labor." And I stand by this statement: it is not, it is the fruit of many people's labor.
> ...is to fundamentally misunderstand economics.
I suppose I should tell my economics professors.