Interesting, I was just thinking about this topic recently, and came upon this article in The Economist today. It describes a progression of US culture that we are vaguely aware of at its component level, yet rarely admit at the macro level. We still proudly state the national myth "in America any boy [sic] can grow up to be president!", yet that is not practical or realistic. In fact, if you look at the most successful 500 people in the US (defined in terms of wealth and power), I doubt you'll find any stories of a nobody arriving at America's shores with 50 cents in his pocket.
Which leads to a sidebar issue, that is, how we define success. Is the CEO of America really more successful than the social worker meeting all of his/her subsistance needs, and very comfortable in their skin? That for another rant.