It's a good point. I would think that the best college football coaching job in America would be to coach one of the top G5 programs. So long as you have access to the CFP, you've got a much easier path to getting there than say, at Purdue in the B1G. Rack up wins, and you could become a god at your school and still make many, many millions of dollars doing something you love.
I understand the counterargument of course, - that these coaches are usually hyper-competitive types who do it not just for the money, but also the ego boost of competing at the highest levels of college football. But based on recent experiences (Taggart, Frost, Herman, etc.) it seems way more likely that you'll end up losing too many games and getting fired pretty quickly at a place like FSU, Nebraska, or Texas, because the expectations are so ridiculously high and largely unachievable.
Just my opinion, but it seems the ideal situation is one where you coach, say, USF to multiple AAC championships, which eventually gets USF into a top-tier conference, and you try to make your mark from there - a platform where you are already beloved and less likely to get curb stomped in a year or two if you don't win 10 games each year. In the meantime, you're set for life financially.