There is an unstated assumption in lot of thinking about inequality, i.e. there is somehow a fixed pie of wealth, and the rich have an unfair share of the fixed pie. On the other hand, if we assume that there is an expandable amount of wealth for all practical purposes, then the question of the "unfair share" goes away, because you no longer need to fight for share of a fixed pie. So, is there a fixed amount of wealth or not? Let me tell you a story.
In a primitive island, there lives only one tribe, a farming tribe called Xulic. The tribe is ok at farming and lives at a subsistence level. One day a young, intelligent guy named Xilcor figures out that he can make a special plow that will allow the farmers to plow the land, sow the seed and create small channels for irrigation, all at the same time. This will allow each farmer to use less seed and farm a larger parcel of land. There is no problem of additional land, since the island has lot or unused fertile land. In fact the innovation will allow a production increase of 100%, or doubling of production. The only caveat is that the only person who knows how to make the pow is Xilcor. Xilcor tells the farmers that he will make the plow, repair it and sharpen it and keep it in good condition, all for 10% of the output that they produce. The farmers agree, since they still get to keep, 1.8 times their original production. With 500 families in the Xulic tribe, Xilcor gets to earn 50 times a normal farmer, so he becomes very rich in comparison to the tribe. Of course all the farmers are better off too.
So, now comes the quiz, who did Xilcor steal from to become rich? Was there a fixed pie from which Xilcor took more than his fair share?
This is a simple example, but there are a lot of these in the modern world. Apple, Intel, Google etc. a just a few examples of companies who got rich because they provided something valuable, not because they took an "unfair share" of a fixed pie.