Mobile is where the money is. Many casuals won’t pay $59.99 for a game but will get a free game and pay $0.99 sixty times with nary a care in the world lol.
You are not wrong but in this particular case the money comes from die hard hardcore fans who spend literally thousands of dollars yearly in the game, there is even a guy who has already spent over 70k dollars on it.
Being a part of this community i can tell you that a lot of these "whales" (and F2P players like myself) are indeed console (and PC) players as well as forum goers, who just happen to be big fans of the Fate franchise as well as young adults with a lot of disposable income, and thas how they (the "whales") choose to spend it.
Which only serves to remind me the POTENTIAL a big budget exclusive Fate game would have, but it aint happening...