The trouble with trying to figure out what a college education is worth is that there's no control group. On average, the kids who go to college have more spunk (or whatever you want to call it) than those who do not. If there was no such thing as college, they would be higher achievers anyway.
This is not to say that the value of a college education is insignificant. It's just that there's a lot of "correlation not causation" and flimsy self-serving math in most of the arguments being bandied about, including by President Eisgruber in his Commencement speech.
If the returns on a college degree were truly as high as he claims, Wall Street would have long ago figured out a way to get you and me to fund everyone's college fees. The student who couldn't afford to make this awesome, no-brainer investment might choose to give away a percent or two of that "9 to 16 percent" annual return, and graduate with most of that future earning power intact, and no loans. Part of their future pay goes to this fund, and everyone is happy.
(The 2014 Federal Reserve article in the footnote uses "15 percent" in its abstract. The actual number was nine in the seventies, 16 by 2001, and "generally between 13 and 15 percent since.")