> 400sqm is absolute luxury in Europe, and plenty of space for a massive detached house with a garden and garage. A house on the high end here sits on less than 150m2 (northern europe).

Just how "massive" can that house be with a garden (say, 35sqm) and a garage (36sqm)? You can probably build a fine house in the remaining 330sqm, no doubt, but I'd hardly call it "massive". Maybe "generous".

OTOH, it might be a point-of-view problem: I'm in South Africa, with a 700sqm building on a 2000sqm plot, in a nice area near the train/bus stop, near all amenities.

It's definitely a point of view problem. We currently own a 90sqm, 3-bed house in the UK and it's not small by any measure here. On this street there are definitely smaller houses than this and people live here with families just fine. Also quite a wealthy area not a dump.

From that point of view, 400sqm sounds positively like a mansion to me. Sure, would love that much space, but I have no idea if houses this large even exist anywhere nearby to buy, I've certainly haven't seen any.

Exactly. The largest homes around here are barely above 200sqm, and cost 2-3 million. Most houses have two or three floors though.

Yes. But birthrate is only half in the Europe compared to the U.S.

And what does that have to do with anything? The USA would need 3 billion citizens to rival the density of the Netherlands.

Or are you implying you need a 500sqm house to raise two kids?