I completely agree that there don't appear to be any controls to validate the data. We are left to speculate on what they might be. It would be instructive to see what quintile poor kids who drop out of school end up in, as well as what quintile wealthier kids who go to college end up in. What we're comparing here is certainly not directly comparable, as there isn't any proper normalization.
I did not mean to impugn the data, only the interpretation. I think the data tell a good story. Do you have reason to doubt the accuracy of the data?what quintile poor kids who drop out of school end up in
If we found that many poor dropouts become rich, or many rich graduates become poor, it might tell us that there's more to the story than family wealth and education. But I think that the data provided already contradict the thesis that "Making good choices doesn't matter, all that matters is starting out rich."
I don't doubt the accuracy. I'm just not sure that it proves what they say it does. One needs to compares apples to apples. That said, I don't doubt for a minute that being born into a wealthy family gives one some tremendous advantages. But that's the problem. The conclusion seems self-evident, so rigorous controls are considered unnecessary.