There's the tough part. Money buys houses in good school districts (or a spot in a private school) which buys fewer highly-disruptive peers, a much better worst-probable-outcome for available peer groups, and a safer (=less stressful) environment. It's hard to live on the cheap housing-wise with kids, since housing costs are a proxy for school/peer quality, and housing's a big percentage of one's spending. Plus it's harder to find housing in good school districts with enough space for more than ~1 kid in car-free commuting range of business districts in most cities, et c., et c. Harder to achieve that paid-off house which is so very important to early retirement. Plus, you've really got to maintain decent health insurance, which in the US means steady employment with a somewhat stable company.
Then you're both working because you need that money to cover the higher priced housing without risking rapid homelessness in the case of a layoff, but now whichever of you's lower-paid and might otherwise stay home is probably working around or below minimum wage, effectively, because child care is so damn expensive.
Whole thing seems like a trap designed to eat all your money. Having three kids took us from "will probably retire very comfortably by age 50, without even having to try that hard" to "will very likely never retire".