What's wrong with only moving up one quintile? Why does the "liberal" dream of success always have to involved rags to riches? How about rags to average? Why isn't that acceptable?
If we live in a meritocracy, or something attempting to be mostly a meritocracty, then movement beyond a single quartile would reflect that. More than a third of the population would swing from one end to the other due to the distribution of people's ability being spread fairly evenly throughout classes.
Why isn't that acceptable? Because as a society we ALL do better when those who have ability are able to realize it, or come very close to doing so. Class mobility then is a reflection of the efficiency of a society to put people in a position to succeed and raise the tide for all the ships. The lack of class mobility that the US has demonstrates inefficiency as birth leads to power and wealth despite ability or achievement. Those in the lower rungs aren't given access to make positive changes while those in power are anchors dragging us all down.
Do you know why we fought the revolutionary war? Do you understand one of the more key elements of the formation of this country was built upon the idea that someone's worth was their worth? We escaped monarchical rule and society for a reason.
The problem is the weak have held power for too long. If everything was purely merit based, a bell curve would put most of them out on their ass and into the gutters they see fit to allow everyone else to wallow in. Instead they use their power to grip on as tight as possible and put as many barriers in place as they can to keep the status quo.
The dream doesn't have to be rags to riches, which accordingly points to riches to rags for others. You raise the floor to something reasonable so that everyone has a nice standard of living, the result of living in a robust modern society. From there you provide incentives for merit so that those who can will be able to rise up and contribute more. Insanely more in some cases.
I'm just flummoxed that you would suggest our society would revert to something similar to the colonial rule that we broke free from.