It used to be (and maybe still is) that in Spain, if your house wasn't "finished" you didn't have a huge tax bill. So it was usual to see the top floor still "under construction". (Very sensible!)
We also saw topless new buildings in Greece but were told that this happened because banks wouldn't give mortgages, so you could only build as much as you could pay cash for. It might take years before people could afford to finish the building.But as far as I can tell, all these topless buildings (in Central and South America) were previously inhabited -- caught them on the way down rather than on the way up.