I see careers and families like being a sports team player vs a coach. In one's career, we love the personal challenges that can go with a career, the individual achievements and rewards that come from "winning". But as a parent, our job is to develop "our players" (our children) into the best human beings they can be.
Some people excel at one role vs the other. Other people excel at both. Some people simply want to be "on the field" so bad, they don't want to "coach" someone else.
For me, while I had an amazing career going from entry level auditor to Senior VP at Merrill Lynch in less than 10 years and CEO in less than 20, it wasn't until I was forced to retire at a young age for health reasons, I became aware of how rewarding it can be to help your children become all they can be. You come to realize, your career is the present, but the time you invest in your children will shape the future.