Because this compares present day cost to all earners (not sure how they normalized for graduate degrees, etc.), there is a huge recency bias. I majored in humanities and minored in sciences/math about ten years ago. Even counting my piddly graduate stipend (again, in humanities) for several years, my return rate of return is over 20% (IRR). If my school had cost twice as much, as it does just ten years later, the rate of return would have been less than 10% as predicted.