Harvard does not have "the best and brightest" students and that's a meme that needs to die as is discriminatory to literally all the other students in the US and the planet.
You are nitpicking. It is an elite institution that still attracts elite class people or else it wouldn't be worth so much to so many groups. There are hundreds of universities in the US, many of which have no kind recognition of the kind Harvard has.
One could also call it a bubble. Last as long as it lasts, which is as long as the stakeholders believe in it.
I think your argument doesn't hold. Just because people still believe something to be the case, doesn't mean it really is the case. It being "worth so much to so many groups" just means they believe in it being worth as much. A well formed argument would come up with examples of the brightest hailing from Harvard and perhaps statistics about achievements of former Harvard students.
Only if you look at one aspect of the school: A bubble wouldn't produce a cadre of skilled people that move multiple fields forward. The elite nature of the institution comes from people maintaining that elite status through accomplishment. You don't need a "belief" when the school continually produces many examples of excellence. Thats just hard evidence.
I think it may have been an [un]intentional callback to Trump saying that about who "Mexico was sending over the border" - at least that's how I interpreted it.