I'm not even sure where "houses got expensive" come from. Houses certainly did not increase in price (per unit of area) in last ~80 years, inflation adjusted - they tightly fluctuate around the same point. Housing affordability is in fact 4th best in the US among all countries in the world, and it got better in the last decades (although with fluctuations, and periods when it was getting cheaper were not pleasant as it meant millions of people going under).