Wouldn't it be better to just set it up as an official tournament instead of setting it up like poker? I mean sure if two players were able to agree that they'd bet on a match then yea feel free, but I don't think anyone would do such a thing, officially at least, since chess is probably one of the most skill-intensive games out there where there's close to zero that luck can play into, especially if you go to the top level players like Magnus Carslen and other gms.

Though I guess if it was about the money, then yeah, FIDE would have nothing to the 2 mil pot but then again, I don't think gms (or anyone good at the game really) would have the feel to bet that much to play against each other nor would they even agree to such a thing.