rationalskepticism.org

10% poorer for many means selling the house, in a market where values are crashing because others are in the same boat, so it may not be possible to sell for more than is owed, which means losing the house to the bank. In such a market rentals may increase in value as demand for affordable rentals increases, so Joe soap may lose the house and then still have to rent with payments close to what would have kept the house, but now he has a bad credit rating, so he can't get vehicle finance when he has to replace the car....

All generalisations, but not exaggerations, that sort of thing happens easily, it only takes a few % to hit the middle class hard, people usually live closer to the edge than they will admit to themselves.