This is not a useful model; in fact, things are quite bad here. I just wanted to say that US homeownership is absolutely exceptional, has no analogues anywhere else, and exists only by means of extensive government support. In most other countries, buying a house in your thirties is absolutely unimaginable.
What age is reasonable? Okay, maybe not 30s. How about 40s? The way we are headed most GenZs are not going to have enough to be able to afford a house in their 40s or even 50s.