The long and the short of it - it's not entirely appropriate to think of real estate as a completely different type of asset class, immune to the vagaries of bubbles and speculation.
Shiller’s gloominess has been widely noted. He thinks we are under the spell of that familiar goblin, mass psychology. Lemming-like, people are buying homes merely because they expect that prices will rise. This certainly holds for speculators, like the manager of a rental-car agency at the Tampa airport who confessed to a customer (an economist) that he owned no fewer than 20 condominiums. And it explains some of the impulse to buy second homes, which are closer to being tradable assets than a primary residence is.
But neither is it appropriate to think of it as being the same. Real estate is much stickier. Quoth The Times:
This is the problem I have with the real-estate-equals-dot-com argument. Most homeowners buy to have a place to live. If prices fall, they react precisely unlike stock traders; rather than bail out, they stay put longer. Every share of Cisco may be for sale every day, but every house is not. Case, Shiller’s partner, tracked 628 home listings in the Boston area during 2006, as prices began to fall. After four months, the majority remained unsold, but the sellers lowered their asking prices by only 3 to 4 percent.
But what I liked most about this article was it's treatment about the value of leverage in real estate investing.
Suppose the stock market did rise 10 percent; after a year you would be up $5,000. Whereas the gain on your home would be 5 percent over the entire purchase price — or $11,000. Over 10 years the gap becomes huge — not to mention over 20 or 30 years. This is the little guy’s (and also Donald Trump’s) trick for accumulating equity: leverage.
It then goes on to talk about how leverage is theoretically practicable for investments in other asset classes, but the truth is that the lending rules for real estate are much more forgiving. If stock prices go down and you are leveraged, you're forced to cover immediately. If that held true with real estate, as the author points out, very few of us would be homeowners. Overall, one of the better articles I've read on this subject.