[travisb]

But that's not how it'd work in practice.

In practice the spiteful billionaire will monthly send you offers $10K over the higher of your estimate or fair market value. So you'd be moving every month and incurring all the moving costs continually, or just continually dealing with the legal dealings of such an offer.

The transaction closes and the billionaire just sells the house at a small loss. The situation is asymmetric because the billionaire never actually uses the house.