It does make you greedy when you're trying to get back the gil you invested in something that's not even meant to be profitable, but something to sink money in and maintain for a long term, it's rather expected to you will loose money when getting rid of it, this is exactly like real life housing,

The problem here is SE housing system as it is;

-Houses should be account wide (able to be accessed from all your characters)
-Only 1 house should be allowed per player
-You should be able to switch houses more easily (like when you buy a new plot, your old one get's demolished and you get a discount in the new one)
-You should be able to demolish your house if you want to, without waiting 45 days

House selling by players shouldn't be allowed anyway, it creates a bad market.