When I wrote about what a ridiculous idea it is to donate $150 million to Harvard, I emphasized how preposterously rich Harvard already is.

But that’s actually only half the reason. Down the road at MIT the endowment is “only” $11 billion, much smaller than Harvard’s $32 billion. But donating money to MIT is only very slightly less ridiculous than donating money to Harvard. Not just because $11 billion is a ton of money in its own right, but because all highly selective universities are terrible targets of charitable donations.

This chart from The Hamilton Project at Brookings shows why.*

Basically what you see is that highly selective institutions are institutions for kids from affluent families. You’ll often hear that such-and-such a donation to an already-wealthy institution is a great idea because it’s going to financial aid. But when only about 5 percent of your class is coming from the bottom quarter of the income distribution (and we can assume that very little of that 5 percent is coming from the really truly poor) then even this financial aid is extremely poorly targeted. Meanwhile, the demographics of highly selective institutions reveal that highly selective institutions remain what they always have been—mechanisms for the perpetuation of inequality and hierarchy.

If you took a time machine back to 1914 and proclaimed to the world that the Ivy League was an exclusionary club aimed at the perpetuation of an economic and social elite nobody would have been surprised. But about halfway between then and now, elite college campuses came to be associated with left-wing politics. And, indeed, college professors have, on average, political views that are way to the left of the median American. But the basic social role of the elite, highly selective institution hasn’t changed—they are both elite and selective, not democratic or egalitarian.

If you want to do something useful for low-income people, give them money. If you want to do something useful for the education of low-income people, give some money to an institution that educates kids from low-income families. That could be a community college or a public charter school or an after-school program or neighborhood school or whatever you like. But it’s not going to be a big, rich, famous school for kids with super-high SAT scores.

*Correction, Feb. 22, 2014: This post originally misattributed a chart to Susan Dynarski. It is from the Brookings Institution’s Hamilton Project.