The thing is, there was only ever one good billionaire and he gave his money away to such a degree he was no longer a billionaire. While Mark Cuban has done good, surely even saved and improved many lives, he still has a billion more ways to do so. Plenty of good millionaires out in the world, there are no good billionaires.
The mere concept of a billion anything is so hard to comprehend that it serves repeating.
One million seconds is 12 days. One billion seconds is 32 years.