The US is developing a self-perpetuating class divide between the upper middle class and those below. The children of upper-middle-class parents receive such advantages in upbringing that they can usually claim all the advantages afterward.

Social mobility is important, but offering a decent life even to poor people is even more important. That would also reduce somewhat the perceived importance of making sure your children don't end up with somewhat reduced social position -- it would not doom them to poverty that strikes upper-middle-class parents as horrible.