He's just a stay-at-home parent. It's a completely conventional thing. Let me go ask my Mom how she "retired" at 25 and lived off her savings (and also Dad's wages).
The socially acceptable way to be a stay-at-home dad. I am not a failed breadwinner, I am retired and spending more time with my kids.
Add up how much a nanny, preschool, etc. costs and compare it to a non upper tech salary, and you will quickly realize that stay at home parent != failed breadwinner. Especially when you’re starting to account for more than one kid.
I am not suggesting that being a stay-at-home parent doesn't make sense, just that the "I am retired" is just cover for a man who is the stay-at-home parent. While it shouldn't be this way, unfortunately many see a stay-at-home dad as a failed breadwinner.
Many people don't see it that way. People are generally understanding of changing circumstances and don't hold others to antiquated notions of masculinity.
I don't disagree, but many don't and that is where the need for cover comes in.
I think having one parent home looking after the kid is very important for the kids development, it doesn't matter which one stays at home in my opinion.