What do you actually want to do with your life? There are careers like politics where personal connection that are gathered during university years are very important.

There are other careers such as starting a startup where personal connections with high status people might not be central and a lot of the YC founders don't have them.

Either there's some sort of self-selection, or do graduates from there have better prospects than graduates of 'University of X, YZ'?

Why "either or"?