The cause and effect there is wrong. Saying that wealth causes success in school is like saying that an increase in the use of air conditioners causes people to go to the beach, or that Christmas shopping makes the days get shorter. There is a different factor causing both.
Wealth buys your family quite a lot of relief. Not having to worry about eating, or being shamed because you eat the free lunch for poor kids, or having access to better schools and computers and so forth are all huge compounding factors for school performance.
This is with ignoring that wealth quite literally buys you seats at various colleges, tutors for personalized lessons etc.
Which leads into my original point that any discussion about the value of unschooling cannot be done without taking into account the income and wealth of families that went that route.
