I grew up in a fairly large house (I don't recall the size, but two floors, 6 bedrooms, kitchen, formal dining room, living room, family room, 3 bathrooms, basement filled with junk; so, fairly large -- semi-rural Maryland, where space was cheap in the 80s/90s). My parents weren't hoarders, though they did accumulate stuff. After my sister and I moved out and my mom passed away, my dad lived in a giant house by himself, couldn't maintain it, and also felt like he couldn't move because the house wasn't in good enough shape to sell.
I just don't get this need for more and more space. It just encourages you to buy more stuff that you don't need, and takes more time/effort/money to maintain. I hesitate to "tell people how to live", but this keeping up with the Joneses attitude is a component of what causes cost of living to rise and is ultimately a zero-sum game.
Space is wonderful for doing things like dancing, hosting guests, exercise, communal/family cooking (sprouting many kilograms of chickpeas, fermenting 40+qt of kimchi).
Also, as the commenter below mentioned, we do enjoy hosting people for parties and family get-togethers. We spend a good amount of energy and time and money on these activities that are for the enjoyment of other people.
Wealthy people often build massive palaces to honor their own greatness and inflate their egos, I can assure you this is not one of those homes :).
It's a pattern I found recurring as we were looking at houses: unless you wanted a 100 year-old house (which could be a good or bad idea), there was simply nothing under 3,000 sq ft on the lot sizes we were looking at.
Edit: duh, it's really 800 sqm.
When the kids have moved out, you can downsize to that retirement place in Spain... except that may not work as well after the UK leaves the EU.
Does that make Luton, St Albans etc. the 'suburbs' of London?
A good rule of thumb is (or was): Does it have black cabs?
How much carbon is emitted cooling and heating an 8k sq ft home in Utah? How far do you have to drive to do things?
Overall, the valley we live in has pretty much everything we could want, from a retail perspective.
A nice small-town grocery store about 3 mins away, and larger national chains further down the road.