Without exception, my male friends with kids have significantly reduced their time and energy spent on their jobs to focus more on their small children. They all say that their kids are the most rewarding part of their lives. Most have highly-paid professional jobs. I expect to do the same, at least for the early years, when I eventually have children.
This seems to be a huge shift from the previous generation. My father and most of his peers worked long hours and contributed little to childrearing.