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.