I think a large amount of people that speak about the amount of money this game makes are severely underestimating how much companies spend on marketing. I don't think it would be wrong to assume, especially with the recent push in advertising this game has gotten, that a good chunk of the budget doesn't just go into other games or even this game but into the marketing for the game. Whether this be ads, commercials, collaborative deals, live events, etc etc.

Yes the game is monetarily successful, but it most likely goes into promoting the game which I think makes logical sense. I know a lot of people say things like "Small indie dev team" as a sort of jab at the development team when costs are brought up, but again, marketing is very very costly and could take a good chunk of whatever budget they're given for said expansion.