I was considering writing a piece on GTA 5, and how they've grossed more during the last four years than some MMOs have made in their lifetime - without selling a piece of DLC.
Their business model is ingenious. They make the DLC free, but the paywall of [in game money] so high that only people that dedicate hundreds of hours into the game can afford it. Then those people are seen riding around the city with their new things and people without the in-game cash become envious, using real money to buy in-game currency so they can afford the new items, and experience the new DLC.
I think it's an incredible thought process. The DLC is free, no one can complain it's not, but only the players that are extremely dedicated to your game can afford it, while everyone else is subconsciously pressured into opening their wallets.