Because the amoral drive for extreme wealth doesn't stop at a certain level of wealth
Or you can keep living in a Disney reality where uncle Scrooges are the norm and not the exception.
I'd rather believe wanting power for power's sake than this cartoon idea of an old duck diving into a pool of well-polished coins.
Truth is that beyond a few truly neurotic exceptions, the obscenely rich do use their money. Just not all in supercars and yachts, but also to influence what they can.