Devil’s advocate: what you are saying is the ability to fund lower income students is dependent upon the generosity of the wealthy and powerful, through their paying full freight and donating as alums. If it weren’t for that generosity few to no lower-income would be attending.
It is easy to deride the “wealthy and powerful” (and I sure wish I was one), but they aren’t all evil. And I never got the impression Ivies are claiming they are egalitarian meritocracies. The wealth and power is the point.