There isn't that much social mobility, there's plenty of statistics that prove that. The American dream is just that, a dream. Like most dreams, the odds are long. You can reduce those odds, but don't kid yourself that it will be easy.
Do you have those statistics? I'm not trying to be unreasonable. It's just that I've tried looking for this data before, and all I found was that social mobility (in the US) has remained relatively unchanged for about 50 years, and that's probably the best it's ever been.
I think we could do better, but I'm not sure what you are saying is correct, either.
There's a lot out there spinning the same result different ways; but I think that's the general status -- social mobility hasn't changed in the US for decades.
There's rather clearer data that the gap between rich & poor continues to widen in the US, which makes it a bit more bleak that going from poor to rich is still a rough uphill battle.
It's also fairly disheartening when you think of all the things that have changed in the past 50 years, many efforts that should help social mobility. Attempting to stop pervasive lead poisoning, lots of grants and policies to help get poor kids through basic and into higher education, legal and other sorts of efforts against sexism and racism... all kinds of things intended to hopefully make the playing ground more fair for everyone haven't actually moved this particular needle at all.
For a bit more context, also look outside of the US. If you want to live the American dream, you'll have a much better chance in Denmark. Reference here (though I read about it elsewhere a few years ago... can't remember orig src): https://en.wikipedia.org/wiki/Socio-economic_mobility_in_the...
Of the 9 developed countries in that study, only the UK ranked worse than the US.
