Absolutely. I think (hope) that what PG meant in that essay is that the rich people today get there by displaying more "sportsmanship" than 200 years ago. And I generally agree with that. And I think if you compare Bezos and Musk with whoever would rank similarly to them on Forbes list in 1821, you would agree too. But it absolutely does not mean that anyone can get there.
The fact that Michael Phelps and Usain Bolt have won so many medals without (hopefully) juicing or bribing officials is great, and maybe even a cause for celebration for the human race, but it absolutely does not mean that anyone can do those things.
Agreed. The focus of the original article was the widening gap between the top 1% (or 5, or 10) and the rest of the population. I doubt that it will cause "unhappiness". Unhappiness exists when you compare yourself with people within your percentiles (+- 5%).
A plumber in West Virginia is not unhappy because Bezos is so rich. He is unhappy because his welder brother-in-law just got paid after a better paying contract job (or is heavily in debt) and bought a used Audi.
But is it really "human nature"? Go back a few centuries, and everything belonged to a monarchy, and by everything, I mean even your life and your family. Were people unhappy "because of it"? For the vast majority of humans, I doubt it. They had just learned not to compare themselves with the king.
For something to be human nature, I think it needs more time. And if peasants knew that comparing themselves to the king just does not make sense, maybe we can learn to have the same attitude towards Jeff Bezos.