> Having a unit sit vacant an extra 2 months at a higher price might be more profitable than "completing the transaction" at a low point in the market.

Yes. And it is also amoral. There is a limited supply of housing. Holding it vacant is restricting access to one of the very most critical human needs there is. It might look better on the balance sheet but it is worse for humanity. Thus, the need for regulation and legislation that prevents this sort of thing.