[kelnos]

Homes on the market aren't infinitely customizable. It seems perfectly likely that GP would have been happy to buy a home with exactly the amount of space they needed, but such a home was not available at a price they could pay. (Maybe they settled for a slightly less-nice neighborhood, or a slightly less-nice house, that just happened to provide an extra room or two.)

Even if that wasn't the case, I don't see a problem with buying slightly larger than is necessary, because (for example) perhaps they're planning to have a couple kids in the next few years, but will rent out the extra space until then. Moving is transactionally expensive, and expecting someone to move every few years as their space needs change is unreasonable.

Regardless, you seem a bit overly judgmental about this entire situation, and about someone you don't know at all.