I would argue that most billionaires are the personification of diminishing returns. At a certain point a billionaire takes more from Society than they offer.
Oprah Winfrey never really offered anything that advanced Humanity and now it seems as if she is taking advantage of people who have suffered from a natural disaster like the Maui fires to buy up more land.
Jeff Bezos' Amazon is now a hinderelance to far too many entrepreneurs to be considered anything but a burden on far too many lives. What good comes from Amazon stealing the ideas and products of individual sellers on the Amazon platform and undercutting their prices to put those smaller sellers out of business?
The Sackler family, owners of Purdue Pharma which lied about the addictive nature of the pain medications they offered, causing the opioid epidemic in the United States made billions. They did it while killing the same number of Americans in one year that died during the ten years of the Vietnam war. How does their contribution advance mankind?
In 2018, I wrote a book highlighting the problems Humanity would face if more power, wealth, and control was funneled to a small group of elite individuals, groups or organizations. In my book, I provided solutions (from myself and others) to the inevitable problems and also a means for the Public to analyze, compare and contrast the words and deeds of those we choose to follow against reality. In my book Solutions: Enough complaining. Let's fix America.
In "Solutions...", provide the means for readers to disseminate information as provided by their news sources of choice, their elected officials, and any other authority they chose to follow. The book also offers a means to hold their leaders up, not just to a higher standard than is currently accepted but to one that would improve their lives and the lives of those they care for.