Agree with all of the above, however no-one has said anything about what the wife & kids think about you pursuing the whole flying circus - & I think that's the clincher. Furthermore, it isn't something you can plan for. Either you get lucky, or you don't. In my case I just got very lucky, because Mrs. Bunglerat was my biggest fan/supporter when I embarked on this crazy adventure. A lot of partners simply wouldn't have put up with all the crap she had to endure for the first few years (I know I wouldn't!), but she stuck by me all the way. When I was feeling the strain, she propped me up. And on the few occasions when she felt it, I reciprocated the gesture.
How do you do it with wife & kids? By having an awesome wife & kids. I hope you're as lucky as I was/am in this regard.