I am probably quite wrong on this, but I have always believed that the people smart enough to get into MIT, Harvard, Yale, etc. were probably smart enough that they didn't even truly need to go there. It's more for connections and a formality than for pure educational attainment.
For example, Bill Gates left Harvard after two years. He did quite fine without graduating by most metrics. I imagine he would have been quite successful, perhaps in a different way, had he not attended at all.
They may not have needed to go, but they almost certainly received advantages for having gone.
Even Billy G would have had two years of knowledge of people whom he could tap - and if you go back and research early Microsoft, I bet you'd see evidence of that.
For example, Bill Gates left Harvard after two years. He did quite fine without graduating by most metrics. I imagine he would have been quite successful, perhaps in a different way, had he not attended at all.