Football coaches don't know when to get the heck out of dodge, and we have witnessed this at some of the most prestigious programs in the country. Guys who are the reason certain schools are as big as they are today have stayed in college a lot longer than they should have.
The reason this happens is quite simple. Coaches have been around the game their entire life and wouldn't know what to do with themselves if they were ever forced to walk away. Some people are just wired to work constantly and when your work is your passion, leaving can be your worst nightmare.