Mobile games are designed to rip you off, especially if they have a Gacha system. I play exactly 1 mobile game at a time (2 at most, although the second one usually only gets 1 brief login per day, if even that) and if they get too grindy or start getting greedy, I just quit.
If I somehow like a game for its story or whatnot, they'll get like $1 a month from me and they'll LIKE IT! If I'm feeling generous, maybe I'll drop $5 on them in a month. "You're welcome" mobile game developers.