My buddy got a sweet deal buying a condo in Dupont, when the building he was renting in was redeveloped. The first step was for a majority of renters to form a tenant association to negotiate with the owner. Since the tenant association had right of refusal, with statutory delay periods, they could essentially gum up the works on any alternate offers. It made more sense for the owner to (a) buy out the renters who didn’t want to stay (for a $10k bonus or whatever), (b) sell apartment-turned-condo units to the remaining renters at negotiated submarket rates, and (c) sell remaining units at market rates.
Another neighbor bought her house when her roommate/landlord decided to move out of DC permanently, and let her have it for a very good price. They kept the real estate commissions, and he didn’t have to worry about TOPA issues. Otherwise, an expedient thing for the owner might have been to use the entire house for personal use for a year, after which the former tenant would no longer have the opportunity.