I think that's overly simplistic. At least where I live people usually buy one house (if they buy one) and keep it for the rest of their lives, so the size is already determined by the amount of things they own, or how much space they need. Just that I've never seen this as a factor, you usually buy what you can afford, not as large as needed to fit your stuff. Stuff just happens to amass and even a small house can be unimaginably full of things without looking like it's full. When my parents sold their house we filled up 2 vans just with tools from the shed. yes, it was a big shed, but it wasn't cramped.