How Do Housing Bubbles Start?

Bob Greene argues that real estate cycles should primarily be understood as being driven by animal spirits. He says lenders were lowering their lending standards just before the financial crisis. This is because they thought, well, home prices are going to be 10, 20% higher before you know it,. So why should I demand 80% down, 20% down payment? Brown: "I don't think there's a clear distinction between credit and your demand"