I guess they can thank the Big Ten Network for that.
Take a look at total athletic revenue by school and it tells a different story.
http://sports.usatoday.com/ncaa/finances/
Believe that depends on how and what the schools themselves want to report (i.e., no set standard as to what is reported under these figures) - for instance, ASWP doesn't even report. Additionally, it is from the "2015-2016" academic year (i.e., 9/2015 to 9/2016), not last year -- IOW, it is two years old and from a period where PSU's Revenues just on football would be far lower than they were last year.
2015-2016 year was the most recent year the NCAA has available. I expect Penn State revenue will have climbed in the last two years, but that doesn't change my position. Yes, Ohio State, Michigan and Penn State have three of the highest paid coaches right now, but my bet is that halfway through his contract Franklin may not even be in the top ten highest paid (I do not know details of Meyer or Harbaugh.)
Yes, these three schools have big stadiums, but stadium size is only one factor in coaches salaries. Total football compensation includes other factors.