You could get any head coach to eat dog sh!t right off the grass if you paid him enough money. This situation is ALL about money.
Alabama, after a decade of losing, backed up the dump truck of cash to Nick Saban's house and said "you WILL be our head coach. How much do you need?"
That wasn't it. Saban chose a program with a top-10 local talent base after he was on the eve of getting canned in the NFL. Plenty of coaches turn down the $ for two reasons: first, if they think the job is a career-killer, then the $, long-term, is not a good investment financially; and second, many coaches are as motivated by legacy and success as they are by just money. The $ being circulated as an offer to Gruden was in the Saban range with a bigger guarantee payday (e.g. how much you get if fired.) He still turned it down. The $ being offered to Kelly was a pay raise; he turned it down. The $ being offered to Sumlin was a pay raise; he turned it down. Remember even Dooley and Jones, two relative no-names, were really given $10M+ guarantees to take the job. Why? Because their agents successfully could argue this job is seen as a career-killer, so big guarantees were needed even for no-names to take the gig.