(Actually I consider myself 'rich' - I own more of my own time, can engage in more pursuits that interest me, than most I know whose 'net worth' is quite higher :-\ufffd ie. I chose many years ago, as in intentionally - that aim over other options.) I prefer adequacy to endless more.
Won't quibble much about the 'average wealth' of US VS all others - so long as you won't quibble about the fact of very many living well below that average, the % of Murican children below our own arbitrary 'poverty level' and such. We so love to reduce all human qualities of life - and even IQ! - to numbers that fit spreadsheets.
Clearly Scandinavian countries opted for lopping off the extreme possibilities of personal wealth: at both ends, and the experiment appears viable - for them. Of course they aren't Muricans, just homo-saps generically.
Meaning only - there are other demonstrated options to our present yielding of power once reserved for society - to Corporate interests, unresponsive to any allegiance except a narrow, immediate definition of short-term profits. Obviously then, we could.. opt for reforms of laws governing corporate behavior - in many ways quite more subtle than merely whatever (declining percentages currently) we collect in taxes. (We can change the rules anytime 'we' can buy more legislators than 'they' already own, I presume)
As to whatever you imagine I know of economics - we'd both have to guess what direct experience the other has, of how low income folks actually live here. As, say: the temps of Si Valley, the operations of Manpower Inc. and other facets of survival at $10-12/hr, some even less, in such an environment - often amid highly toxic compounds and sweatshop working schedules. (Unless you were speaking of those theoretical concepts re the velocity of money - in full academic flight?) Or maybe we could count the # of people we know personally, living that life? Would that connote: economics field work, or would it not be sufficiently theoretical to receive official credit?
Dismiss the idea of "the tiny group of people controlling the universe" as you like. Dismiss as well, the practical powerlessness of a substantial portion of all US workers too, but then you'll also have to elide: the present impossibility of even commencing campaign reform, that which goes to the heart of our advertised 'democratic process' VS Corporate ownership of (the selection / propaganda aspect of) that process.
We may even have to look to Europe for any discipline of M$ ever! - just one of our corporations. But as to the division of spoils worldwide? I can't see how this factor can be ignored perpetually, as technology equips smaller and smaller players to do large damage. Perhaps you can.
(Of course too, the entire argument may be rendered moot, soon enough.)
Ashton