Chris Hayes argues in his new book Twilight of the Elites: America After Meritocracy, the real reason that blacks and Hispanics are making so little progress over the generations at qualifying on their own merit for selective academic institutions is because rich whites are hogging all the test prep.
Education Realist, who is in the test prep business, has a post linking to various recent studies of the popularity and effectiveness of prepping for admissions test by race. Here's one table (with score increases out of 1600, not 2400):
Use of Test-Prep Courses and Gains, by Race and Ethnicity
East Asian Am.
So, unsurprisingly, East Asians try the hardest at and get the most benefit from test prep, while whites, who are more likely to have heard and believed ETS's propaganda that test prepping is insignificant, try the least hard and get the least benefit. In the middle, blacks and Hispanics benefit from all the racial uplift programs for them.
This doesn't disprove Chris Hayes' assumption that Upper East Side whites are benefitting from test prep. My guess is that the big losers in this game are naive flyover folks.