I don't know about the US, but Canadian universities spend 3.5-4% of their endowments annually and expect this to preserve the real (inflation-adjusted) value o

I don't know about the US, but Canadian universities spend 3.5-4% of their endowments annually and expect this to preserve the real (inflation-adjusted) value of the endowments. So they're expecting between 5.6% and 6.1% nominal annual return over the long term. Nobody ever invests an entire endowment in bonds; even aside from the lower rate of return, the inflation risk is much too dangerous.