It's a combination of things really. Lack of building when the population is still growing. Encouraging single lifestyle, both by kicking out kids early and s

It's a combination of things really. Lack of building when the population is still growing. Encouraging single lifestyle, both by kicking out kids early and shacking up later. Cases where sitting on an empty property is risk free. Infrastructure increases taking valuable space. Giving early birds great deals compared to today, making them sit on huge housing for a pittance and making moving out a terrible deal. And politically, there simply is no immediate incentive to solve things when the current population of homeowners does not contain enough people to vote in favor of those that don't own homes.