If I am not mistaken MOBOX is giving 500,000 MBOX per season as rewards in ALL their games (they currently have 4 I think including the one above and 2 unreleased ones). I for one is also wondering how this would hold in the long run as I suspect a lot of people especially those at the top would most likely dump their rewards as soon as they get them.

They do have been constantly adding use cases for MBOXes like it can be used for refining/replacing MOMO skills in this game to which MBOXes spent on their games ARE ALL BURNED (if I am not mistaken). I am just not sure if that would be enough to remain the price stable.