my wife was stay at home when I was 30. doesn't change a thing. I earned much less then, and we had a different lifestyle (and less kids :-))

Everyone’s situation is different. It can be done.

I've known many families around that age (+/- 5 years) with a stay at home spouse taking care of multiple kids. It really shapes their lifestyle in a lot of ways (smaller/older house, rarely eat out, rarely big family vacations, clothes/toys often from secondhand consignment stores, fewer/cheaper vehicles, etc.), but that's what's important to them so that's how they've set their priorities. Most didn't come from extremely wealthy backgrounds so its not necessarily like other wealthy people are propping them up, although a few are like that.

It may very well be impossible in certain markets but I wouldn't say its true across every family with the parents being around 30 years old.