[ben_w]

There are millions of empty homes in this world.

I'd assume environmental, but there's also more subtle answers than will fit in a comment box — whatever the cause, it has to be near-global.

China's building loads more houses, still has a fertility decline.

[shadowmnifold]

Surely, the reasons are multivariate with all kinds of interactions and feedback mechanisms between the variables.

It is really a good example of what natural dimension reducers we are, even when we know it makes no sense. It is like we can't but help ourselves to reduce things to one explanatory variable.

My favorite is the news headline "The market went up today because of X".

[hhdhdbdb]

They never say that.

They say: Tesla shares up as revealations surface that the wind is blowing east.

[hhdhdbdb]

Yes I forgot to mention the implied: Homes, that meet code, with connected utilities in places people want to live that are not being landbanked.