I had a roommate who ended up at JPMorgan, and a few more distant associates really hit the jackpot in the Oil and Gas industry.
I will agree that if your life goal is a 100/hr a week investment banking position or some top tier management consulting position in NYC then a big state school probably isn't where you want to be. But you can't study petroleum engineering at Yale so it works both ways.
Of course you're right, these companies aren't the beginning and end of the great jobs available to college grads. If you have zero interest in these jobs, going to the most elite schools is much less important. At the same time, there is a reason a quarter of MIT grads end up in finance and consulting (pre-recession, it was a third). For better or worse, they offer relatively low-risk paths into the upper echelons of corporate America.
Hell Penn is a public university and an Ivy.
Balancing a comfortable income and having a life were more important than striking it rich at all costs.
You don't need to fix the schools, you need to fix the wealth structure.
There is no value in replacing a pack of NY assholes by a pack of IA assholes.