That's a problem of regulation/NIMBYsm right? Because if someone has 'captured' entire market, it means no one is living in those houses, they are just purchased and locked up. Meaning, they don't consume any resources, don't result in water, electricity networks etc. being strained, and don't result in extra congestion. Meaning, there's no problem to just build more. Unless regulations/zoning prevent it. So fight zoning, not "inequality".