While the US was never an economically egalitarian nation, at least in recent history, it has fallen to become one of the least equal among any countries in the world that likes to consider themselves democracies. Combine this with the decline in social mobility in the US that is getting progressively worse by generation, and it is hard to conclude that the American Dream does exist except for a few.
Source: Ten Men, $1 Trillion, and the Personalization of American Capitalism – CounterPunch.org