Factoring in 5-7% annual return on investment, it's only about 25-30k per year, not 50k. (Given P(0) = 0 and P(n) = P(n-1) * 1.07 + $25,000, P(20) would be $1,024,887.31.) Perhaps still a bit high, but not too far off, especially considering that the second child probably has a lower marginal cost than the first.

Fair point, although most people don't get that kind of ROI for their extra money in practice (instead most of the money is "lost" in all kinds of fun things).

I could argue that $25k/year is still very high compared to my experience, but I have no idea how much daycare, healthcare and education cost in the US. It probably makes no sense to compare costs to a country where I would earn over double my current income...

Maybe it's counting college costs or something.

it's everything over 50 years. It makes a difference having a kid at 25 vs 35.