You make some excellent points – but one thing you have to keep in mind is that most homeowners, and most people that own second homes or investment properties, did not purchase their properties at the top of the market. If they did buy property at the top of the market, say last summer or fall, they most probably traded up and sold another property at a huge profit.
If someone did buy multiple investment properties last summer, they will probably take a big loss on paper, and I don’t feel too sorry for them, but let’s say someone bought a property in San Diego, Arizona, or Florida in 2004, 2003, or earlier – they have had huge profits, and even if prices fall 20 or 25%, they’re still going to be money ahead if they have to / want to sell this year.