I don't know. Only a handful of coaches in NFL history ultimately had a bright future.
That is to say, this league averages about 6 new HC's every season. the statistics on HC's says that 288 of them coached between 1970 and 2021.
How many of them left on their own volition? Probably a couple dozen. That would be close to 10%.
Therefore, an NFL coordinator that aspires to being a HC has a 90% chance of being fired.
That doesn't seem like a bright future to me. That's a really tough job. The whole world finds out that you were fired because you couldn't get the job done. Even if you did for a few years you still get fired for not continuing to do the job with acceptable frequency.
There is a hit to your finances, reputation, ego, and even your family. Your wife and children are not exempt from idiotic over-the-top fans. We all know they exist.
Disappointment should never be turned into anger directed at those coaches who tried to do everything they could to make the team's fans happy. Head Coaches are obsessed with winning. Every loss hurts and when they come in bunches it becomes a nightmare.
When it comes to HC's, I think we should all refrain from personal attacks, name calling, and even hoping for their failure. I think it's two faced and shows just how insincere fans can be when a team is winning versus losing. Obviously I'm not talking about all fans.but there is a sizable group that acts as though they are entitled to have their team win championships and unsuccessful HC's are guilty of sabotage.