The industrial revolution and global colonization changed that, injecting opportunities for an ever-growing section of men; and genocidal mass-war eventually did the same for women. This land of mirth and honey where every man has an opportunity to bootstrap himself is a somewhat fantastical invention. Social mobility might have been higher than average in the US between 1850 and 1950, but anywhere else "where you come from" was always the most important factor in anyone's fortunes.