> Real estate is usually leveraged. You don't simply get to keep living in a house if you are insolvent and owe more on the property than it is worth.

Right, but the problem there is the insolvency, not being underwater (conceptually, you have the same problem if you are insolvent but owe a nonzero amount that is less than or equal to the worth of the property, though if its less you may be able to stay off insolvency by increasing indebtedness -- though that will probably take convincing a lender that your income/expense balance will change soon enough that you won't end up insolvent and overleveraged.)