I'm not sure if anyone has floated this idea before, but I'm sure someone will say if they have.
I'm wondering if Charlie is more or less motivated in the way he represents himself. Charlie is content with a single city, isn't interested in trying to conquer anything in his own right, certainly doesn't want to take over the world. He just wants the 'game' to keep going on forever and so is constantly involved in stirring up further conflict by helping whoever will pay him and then switching to the other side when they pay him for a contract that trumps the original contract. Charlie enjoys the game for its own sake, and amassing the money and favours that extend his ability to be involved. He's a bit like Data's 'winning' strategy in "Peak Performance" - never tries to win, so never risks being destroyed, but, unlike FAQ pre-Queen Jillian, is actively involved in broader conflicts, and so therefore is part of the problem.
And, if the Hippiemancer in the Magic Kingdom was more-or-less on the money, that, ironically, makes Charlie the Big Bad Guy in the overarching plot. If Hamster's true goal (narratively or given to him by erfworld) is to bring an end to the internicine warfare by defeating everyone, then Charlie is the one force that is truly his opposite - promoting warfare not for himself (in the sense that he has no interest in expanding his territory), but simply for its own sake.
No-one, including the reader, believes that it could be that simple because, as Charlie says, no-one believes what he gives away for free. And the reader (and Hamster) got this info fairly 'cheaply'.