Lots of Harvard undergrads are not there to learn. They are there for other reasons. So I would NOT say that Harvard is loaded with passionate learners. Harvard undergrad has a fair number of students who are majoring in economics because Daddy said so, and have no idea of their passions or interests. Some will find themselves, we hope, at Harvard. A few students at Havard are very very passionate about mathematics, physics, English, chemistry or becoming Senators. Just to get another viewpoint on Harvard! Harvard has concentrations, not majors, and the math people there are superb, as are physics, and chemistry, I mean world class. But the undergrads come from all walks of life. The back door to Harvard is wide open. Harvard grad students are exactly like you describe, but you are getting a bachelors degree, not a PhD.