“I am going to go with simple supply and demand. At many top 100 schools there is no shortage of students willing to pay the tuition.”
Ding ding ding ding. Total undergraduate enrollment in the US:
1970 7.4 million
1980 10.5
1990 12.0
2000 13.1
2010 18.1
2014 17.3
2025 19.8 (projected)
More kids than ever before going to college. Which then places a further premium on securing a seat at a selective school.
Also, the arms race for facilities and increase in administrators is totally understandable. The market for college seats used to be extremely localized. Now due to cheap air travel, internet, Common App, etc., the market for college seats is regional/national/international.
Kids don’t just show up at their hometown/homestate college like they used to. Schools now have to market and brand themselves in extensive ways that were unheard of before. And also discount their prices extensively too, since the model (like it or not) is high price/high discount.