I mean it is just like the YC model, 1% of the companies will give outsized rewards which will more than justify investing in the 99%. Same way, Harvard is probably propped up by the 1% of kids who it takes in who do great things and the rest can just enjoy the privilege of being alumni of such a "great institution". These top institutions take in not only unworthy rich kids but also the cream of the crop in science, leadership etc...