I think the key to human motivation lays in finding and understanding the balance between individual and collective well-being. The problem with the systems we employ, now, is that they depend too much on individuals desires, and well-being, at the cost of the collective society. And as a result we have a few individuals who's greed is bottomless, striving relentlessly to own and control everything and everyone, while the well-being of the many, suffers. And as those individuals gain in wealth and power, everyone else's well-being is decreased.
Competition, it turns out, really is not the motivator that serves us best. In fact, it's the motive that divides us against each other, and thereby destroys the fabric of human society.
Whereas cooperation (not competition), in the service of the well-being of the whole society (not just a few individuals within it) is what will serve everyone most fully, and result in the greater well-being, overall. And it mystifies me that we humans are so persistently unable to grasp this simple logic, and implement it.
I think human motivation is an extremely complex topic and that this explanation is also short of the mark. Dan Pink's book "Drive" does a good job of summarizing leading motivation science, as does this video, which is a good summary of the book: