And to tag on to what @Mom2aphysicsgeek wrote, this is actually kind of disingenuous on Harvard’s part—if you dig behind their numbers, you’ll find that they’re saying that for 90% of American families, it would cost less for their kids to go to Harvard than to the average public (that’s a big caveat—for one, we’re not just talking flagships here) without further aid.
I don’t know what the actual percentage would be, but despite the way it sounds, it isn’t true that it would be cheaper for 90% of students’ families to send their kid to Harvard than to send their kid to a public university.