It’s a rental Market. And markets always respond to the demands put on it. As you pointed out, there either needs to be an increase in supply or a drop in demand for rental homes to become cheaper. There is a third option, however. Imagine SF becoming increasingly gentrified, to the point where anyone not working a high-paying tech job can’t afford to live in SF. What happens then is all the lower paying jobs move out of the city and essential services that the tech-eliete depend are harder to find. But, we all know that won’t actually happen. With an increased demand for unskilled labor and service jobs those wages will magiacally go higher in order to entice workers to commute into the city. Isn’t economics amazing! It’s all math, as this article so keenly points out. But this will not happen across the board, even if all housing was that expensive. Reason being, it would only become a problem once the transportation infrastructure (bart, cal train, bay bridge, golden gate bridge, etc) becomes insufficient. People move out of the city to afford cheaper housing, but still commute to their higher paying job. Although, if commuting into SF becomes impractical then companies would begin moving out of the city to make life easier for their emplyees.