Pff, in Switzerland, the mean age of the first-time home buyer is 48, and the mean age of a homeowner is 58. And those are the luckiest and the richest who could actually afford buying a house; many rent for life.
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.