Problem with "walkable" is it means you've gotta cram 5 million tens of thousands of people into a couple of square miles; and I hate seeing people -- I love seeing cars.
If I want the opposite of walkable, why would I move into such a population dense area? If I wanted the opposite of walkable, I'd move to the middle of nowhere, with nothing around; not one of the most population dense cities in America...
Phoenix is literally the 5th most populated city in the USA
Even then, it's easier to be a recluse in a city where you can get everything delivered and never leave your home.
If they move out to the middle of nowhere, they'll never see a car again, and will have no where to go anyway, so what's the point if they have to drive an hour to get groceries where there will definitely be people.