I don't believe in the "fixed pie" view of the economy (does anyone..?) but wealth consolidation is still problematic because the ever-growing pie is rarely distributed among those who actually do the work, and concentrated power is a horrible way to run a free market economy. It leads to abuses that break the assumptions free markets are based on. Predatory pricing, regulatory capture, and buying out competition are examples from the vast toolbox only available to players who have accumulated significant wealth in the past. Slowly but surely the system gets skewed to reward past success and conniving over future success and hard work, which slows down progress and ultimately makes the world a little bit worse place for everyone to live in.
PS. I don't think it's a coincidence that both of your examples of creating wealth are typical "poor people" jobs. Obnoxiously wealthy people rarely create anything because they can simply pay someone else to do it, usually for a fraction of the value of their output.
> the ever-growing pie is rarely distributed among those who actually do the work
That's the Labor Theory of Value perspective. What actually happens in those cases is the particular jobs being done are not that productive. Consider if you could pay someone $10 to do $100 worth of work. Inevitably, your competitor sees you making this easy money, and entices your worker away for $11. Then you entice him back for $12. Then Fred entices him away for $13. See where this is going? The wages go up until it is barely profitable to employ the person.
> Obnoxiously wealthy people rarely create anything
What they do is conceive of it, finance it, and manage it. Those are critical wealth-producing activities. Start a company yourself, and this will quickly become apparent.
> is rarely distributed among those who actually do the work
Scores of millions of destitute people immigrated to America in the 19th century and moved up into the middle class and beyond.
Also, free markets do not "distribute" wealth. Again, that is the fixed pie viewpoint. The actors in free markets create wealth.
> Predatory pricing,
I.e. offering lower prices. Nothing wrong with that.
> regulatory capture
That's a problem with government, not free markets.
> and buying out competition
Nothing wrong with that, either. Lots of conglomerates become so complicated they collapse, and new competitors always spring up.
PS. I don't think it's a coincidence that both of your examples of creating wealth are typical "poor people" jobs. Obnoxiously wealthy people rarely create anything because they can simply pay someone else to do it, usually for a fraction of the value of their output.