Specifically for housing in America, though, more houses don't lower the price. That's because the more housing is owned by an individual builder the more they control appraisal comps. Why do you think they have so much marketing to try to convince you that it's good for the environment?
They are able to get zoning exceptions to build high density, high priced living. Pick any skyscraper residence in America. Nearly all, if not all, are far more expensive than surrounding suburbs.