Duration has nothing to do with it. One should not buy a house while on a temporary visa, period. You should not feel entitled to stay in a country just because you've been there X years on a temporary visa.

If someone gets permanent residency in a country I see no problem if they want to buy a house after 6 months, more power to them.

The abnormality is this idiotic 10+ years time that people are allowed to stay on a temporary visa. This is what needs to end. This is what makes people entitled - understandably I would even say. People are foolish, but I still blame the game, not the players.