Only because that's what college has become. I loved studying my field for four years, free of most of the vicissitudes of life that would otherwise prevent me from being able to focus on an education. I guarantee you a lot of people would like to get a degree simply for the sake of learning, and to become a better person. Hell, I'd take a few classes if it didn't cost like $800 per credit hour. This whole "college as job training" thing is a self-fulfilling prophecy, and none of the innocent people subjected to it are particularly happy with the situation. They are not, crucially, in a position to change that.

reason (3) is social signaling.

elite schools aren't only desirable because they set you up with big opportunities. they are the way for high-school overachievers to signal to everybody how smart and good they are.

elite schools could probably make bank if they just sold a stamp-of-approval from their admissions committees that just said "you are smart enough to get admitted, but were not lucky enough to win the lottery of being given a seat".

> Americans attend college as a (1) rite of passage and to some extent (2) to have access to an influence network of peers and alumni. For elite universities, it's conceivable that #2 provides some real opportunity.

I believe the primary reason is to attain credentials in pursuit of access to more lucrative employment prospects. I think your 1 and 2 are both significant factors, but they are quite far behind the pursuit of credentials.