The more elite the school, the more elite the ppl you meet. The financial outcomes can be easily explained solely on the networking effects of meeting ppl from more powerful sectors of society. No one sends their kids to an Ivy league school to get "Super smart", its to hang around the "right group" for later influence and networking with the "right people".
If you are going to send your kid to one of those, be sure to clearly explain to them that is the point, lest they fall into the trap of studying and getting good grades at the expense of networking. (I leave it as an exercise for the reader to decide which parts of that are sarcastic, and how much. Frankly I'm not sure myself.)
(I, too, leave it as an exercise for the reader to decide which parts of that are sarcastic, and how much. Frankly I'm not sure myself.)