(con't) aren't cheap to sustain, because they require some sort of technology intervention?
Following your logic, we should trash New York City because it couldn't sustain itself if the without the articfical support of electricity
How about this? Let's abandon Wheaton and Silver Spring because the population can no longer be supported by the food that is grown there, and a if there was a prolonged traffic jam on Georgia Avenue, it would be impossible to bring food in--