It’s not just the royal family, other descendants of the french conquerors are also on average wealthier than the descendants of those that had been conquered.
One pretty striking statistic: “Furthermore, Norman descendants also enjoy other privileges, including attendance at the best universities. In a recent study that examined the enrollment at Cambridge and Oxford over the last thousand years, it was revealed that at certain times, Norman names were 800% more common at Oxford than in the general population, and more recently, were at least twice as likely to found in that institution’s enrollment.”
https://www.todayifoundout.com/index.php/2014/10/last-1000-years-families-owned-england/