Your coach Fesi had offers the last few years for more money. He turned them down. Why? Because he appreciates having Sunday off to spend with his kids. Family is very important to him. He basically grew up without a mom. However, he was surrounded by his extended Tongan family. At times there were more than 25 people living in his Sandy home. The patriarch of this good family was his wise grandfather.
The only way Fesi leaves in the near future IMO is if Kalani leaves and he follows him. Kalani would likely institute a program like Navy has - where the coaches do not work on Sunday. Fesi came from Weber State where Jay Hill, another active church member is the head coach. I suspect if Fesi was offered a job somewhere as an offensive coordinator for 500K a year - it may be hard to turn down. (His extended family could use the money.)
Fesi is a good man and will always do what is best for his family. Right now, being at BYU is what's best.