No doubt college HC is a good job. I'm just saying there is less arse kissing as a NFL HC, you don't have to worry about spending a lot of time on the recruiting trial, you don't have to deal with the money stuff, and you are coaching players that are supposed to be professional so you don't have to deal with as much bullshirt.
Also, there are a limited number of college jobs that pay like NFL HC jobs. So even if you include college jobs, there are probably only 60 or so of these jobs available, and some guys, like Joe Brady, didn't really like coaching in college so they are only likely to take NFL jobs.
I'm sure there are some coaches that prefer to coach in college (Saban was one before NIL), but I suspect those are guys that are less likely to be good NFL head coaches anyway.
And in the end, I'm just saying that the vast majority of guys offered an NFL HC job, especially guys that are coordinators in the NFL, are going to take the job. That and even if you can't get your top choice or two, there are plenty of good coaches out there capable of being good NFL HCs.