Aside from your circular reasoning (kids that are sucessful are successful), you could transpose this argument back half a century and have faulty rationale that many whites used to justify segregation of academic institutions at all levels. The success of Jewish students from "less successful" backgrounds once anti-Semitism was largely dismantled demonstrates how this was absurd on its face.
It's not circular. It's like this: You can burn coal in a fire, and you can make the fire bigger by adding coal. You can call that circular, but it's provably true. Kids tend to succeed if they are surrounded by success. Parents set demands, peers provide competition, etc.
As for the Jewish students... well isn't it nice that the law does not block them from moving into the better school districts? The same applies to anybody else. If you are successful, you can move into the good school district. This has been true for about 47 years in the USA. Nobody is stopping anybody.
Don't want to pay? Clearly you don't care about education, and your child would likely degrade the educational environment. Can't pay? It's pretty much the same thing, but with a small non-zero chance of being wrong, and maybe you should homeschool.
It's not circular at all, it is simply a fact that the education system works that way. Why is Harvard prestigious? Because it has a policy of only admitting people who would be successful whether they went to Harvard or not... And "Harvard dropout" carries as much cachet at "Harvard graduate", which should tell you something.
It don't believe that's how it works. Here's another question to demonstrate this: How did the University of Michigan become a prestigious public university? In part, by accepting all the bright Jewish students that Harvard blocked from admission because of racial quotas. The subsequent success and honors of their alumni built up their reputation and donor base to what it is today. So aside from this argument being unfalsifiable and circular itself (those who went to Harvard would've been successful if they didn't go to Harvard, but they went to Harvard...), we would have to accept that all the Jewish students rejected from Harvard we're just never going to be successful anyway, which the historical example invalidates.
