We don't create buyers quickly, but mobility means that a large number of buyers can show up in one concentrated area much more quickly than housing can adapt.
One piece of the US real estate puzzle is that automation and outsourced killed agriculture and manufacturing jobs. Those are the kinds of jobs that have some natural incentive to be spread across the US. Ag, because farms literally take up a lot of space and are spread out, and manufacturing because factories tend to be close to raw materials, ports, or other local resources.
When you get rid of those jobs and replace them with information work, you create a feedback loop with no dampening in it. People want to go where the most jobs are, so they move to the cities. Businesses want to open where the most workers are, so they start companies in cities.
The next thing you know, all the small towns are filled with dirt cheap empty houses because there are no jobs. Meanwhile, every metro area is bursting at the seams.