Do they have a an extra large family? Are they building a larger home because they plan to have room for the grandkids I”H, or because they host zedaka parties or host gedolim and therefor NEED more room? Are they making room for parents? Or for out-of-town family?
Are you going on the premise that they THINK they are better than the rest of you or are they smart in this economy that they can get more for their money right now, so why not think ahead? Just because it is large and spacious does that automatically mean that it is also fancy and ostentatious?