Silly. I assume you're comparing the US to some imaginary Utopia you've created in your mind, because you can't be comparing us to any other country that exists or has ever existed on the planet and think we have not been an overall exceptional addition to what you consider to be the cream of that crop. I would submit we are the greatest country to ever grace the planet earth, but I've course I may be biased a bit. We're far and away #1 in any of these categories:
Healthcare
Social mobility
Access to higher education
Except that's false. Patently false and silly. This is still the best place to move from poverty, and I mean abject poverty to middle and upper-middle class that there is anywhere in the world. And people coming here from India, China and many other places realize and prove this year after year. Educated people from all over the planet come here and show our (generally) sorry and complacent native-born asses how education and hard work lead to great success, here.
I also know several people who make six figures (or seven in a couple cases) and are very comfortable---who came from abject poverty here in the US. A solid, overflowing handful who fit in that category. That I know personally and know where they came from. One that got a baked potato for dinner 6 nights a week growing up and something "special" (i.e. not that special) one other night. Another where there was a plastic garbage can full of rolled oats in the corner of the kitchen and you made yourself and your younger siblings a bowl if you got hungry. Because that was your option if you were hungry. Rolled oats, or rolled oats. I know a man who had four brothers and they got a new shirt to share for school pictures each year and didn't always have shoes. Five boys, one shirt for pictures. Obviously, only one of them was wearing a shirt that fit properly in their photo each year. A couple where the situation was even worse. Crazy stuff. Yet somehow, without any connections, without a dime to their names coming out of high school, with no leg up or privilege of any kind, they succeeded here. To be fair, all were blessed with intelligence but that didn't do it, either. It was a "different" kind of attitude and ethic towards education and hard work that got them there. The same as the immigrants who find the same success. The formula seems simple.
That, and I feel like the ones I know always knew in the back of their minds that they wanted to have some bacon with their oats or a steak with that baked potato. lol
But there are few (if any) other places on the planet where you will find this happening with regularity. Yet it still does here. Every year. Year after year. Education, talent and hard work are greatly rewarded here without any caste system or concern about your race, religion, ethnicity, gender, sexual preference, not a damn bit of it matters to your success. Only your own choices. And it permits the natural transfer of wealth as well. To the right people. Those who work for it and deserve it, get it.