I see very little support to your point. People who are wealthy now are not kids of those who were wealthy in the previous generation. Almost all wealth is self-made, because most wealth is in industries that didn't even exist a generation ago. And, whole lot of that wealth is not even capita, it is salaries. How in the world it prevents upward mobility? If anything, it facilitates it.

I know a ton of people who are rich, like, up to lower centimillion bucks rich (would be comfortably in top 0.01% of Americans). None of them come from wealthy families. Kids from wealthy families mostly enjoy upper-middle class, sinecure jobs secured by their daddies yes. They don't get to worry about anything in their lives, but they aren't rich either, most aren't even in top 1%