There was a great piece in the WSJ today that helps explain part of the problem. I think you need a subscription - but here it is:
It argues the motivation/satisfaction/work ethic/participation issues isn't due to the difference between the middle class and the rich, but the difference between the middle class and the poor.
Once you account for transfer payments to those to don't work, their income is very close to the net income of those who do work. So if you are working and not making significantly more than your neighbor who doesn't, it isn't very motivating.
Apart from the growing welfare state, this is also a product of our affluence and not pushing our kids as hard as previous generations since WW2.