Sure LaVell and his staff might have been underpaid but being a football coach was a nice income if you were the head guy, a good professional job but not something you can work for 5-10 years and be set for life like it is now.
Even good assistants at P5 schools making $500K? That's more than most professional people make. That's up there with Doctors and Lawyers, and high paid executives.
Assistants might have been underpaid but it was more like the difference between a school teacher in CA and a school teacher in Utah.