Class mobility in the US is incredibly overstated. The number one predictor of what socioeconomic class you'll die in is the one you were born in. In fact, we're not even more mobile than other developed countries: On the contrary, at 43% of bottom quintile household-income individuals staying there their whole lives, we rank pretty damn poorly.

Like, sure, it's a step up from "100% of serfs died a serf", but it's not good, either. It's certainly not "the American Dream". Maybe try "the Danish dream".