``More to point...how [are] these ever expanding building booms ... sustained...?'' .d.
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Well since there is no reason to live there, intrinsic to the landscape itself, they won't be sustained for long.
In the other direction, its interesting to see that most cities evolve from the immediate geographical situation, usually waterways, or some other natural feature to the place that makes it both sustainable and logical why to build a city there in the first place. SF of course has the bay, NYC the confluence of rivers, ocean, port... same for London, the list goes on and on.
Some places it takes time to see why a city was built there. Santa Fe for example. Santa Fe is one of the oldest cities in North America. What's it doing in the middle of nowhere? I took a hike up in the mountains behind Santa Fe and looked out over the high deserts. I finally figured it out. The deserts form these long open valleys, and three of these intersect right at Santa Fe. It was literally a natural crossroads. And the mountains produce enough snow melt to feed streams that flow down to the desert---where the water can be pulled up in relatively shallow wells. So that's why Santa Fe is where it is.
In constrast the linear spawl along California highways is not linked to any natural system that provides for its own sustainability. They literally are in the middle of nowhere for no reason other than the abstract economic rationale of greater profit. As a consequence these communities take ever larger and larger shares of technology and natural resources to keep them alive. Eventually they will rot and blow away, like all the slap together mining towns of the gold rush, or the desert land deals that used to stretch out of Mohove, Needles and other places in hell.
CG