Maybe when in their 40s, they've made enough to be effectively retired? Otherwise, given the commitments you mentioned, they'd likely never be in a position to

Maybe when in their 40s, they've made enough to be effectively retired? Otherwise, given the commitments you mentioned, they'd likely never be in a position to branch out. Maybe some founders are younger because that's the window. They are old enough to be at the staff level (experience) and yet young enough to not quite be ready to have children. Whether they know it or not, startups usually fail within the first year and the most common difference between year acquired and year founded is 3. If they fail, they'd likely do it just in time to settle down and have children on schedule.