I'm one of those senior Captains you speak of. You've missed the mark with your reasonings why I and others stay. Quality of life exists at the regional level as well when you're somewhat senior. To go to a major, im taking a heck of a pay cut, I'm likely commuting and working a crappy schedule over the weekends and on holidays. The pay at my airline for a 20 year guy is well north of 100K/yr, even more if a LCA. If you can't live on 120+ a year, you likely can't live on 200K either.
I'll take a comfortable salary and the ability to watch my kids grow up as well. The drive to achieve a major airline captain salary has a cost that many don't realize till the kids are out of the house.