I'm sure there are plenty of reasons, but the simplest and most significant (to me) is the rise of the complex home mortgage. These BYO homes were typically purchased when the buyer was able to buy it in full. Remember that in those days, there were no such things as credit cards and modern financial practices. The idea of purchasing a home without a mortgage is a foreign concept here; in fact, there are volumes of advice around that oppose buying a house in full because of the risk. Before the mortgage was the norm, people bought homes with money they had, and protected their property like it was a sovereign nation. The popularity of the loan, and that "everybody does it", continue to be one of the factors that are driving up home prices to this day.