I have no idea. My guess is the obvious: To them who have much, more shall be given. MIT has a huge endowment and very great professors. Their money attracts more money and their talents attract more talent. If you were a budding young Isaac Newton, would you rather go to school at Westchester Community College, or MIT? Which of the two institutions would you rather give a billion dollars to, with the goal of advancing nuclear physics, not helping welfare moms get their Associates’ degrees (which latter is also a very honorable philanthropic cause!!!)? I do not think there is any secret.