Um no. Buying the dlc does in fact support the game. Why do you think this game got supported this long with more characters, stages, tournament money, etc? It sure wasn't the game software sales which was worse then previous games. I'm not defending that the shit isn't overpriced/bad quality/whatever, but overpriced or not the money does not disappear in thin air. It goes to the upper management pockets and that money revenue is justification of them giving the go ahead for TN to keep supporting the game.
Remember this game support could have ended years ago if it was a commercial failure logically. I'm personally fine that their are plenty of whale consumers literally keeping this game relevant development wise by buying a bunch of overpriced costumes, themes, gravure videos, for their favorite character. That is because the endgame actually benefits me and others too. Ironic thing is that if dev support hasn't gone this long then the PC version would likely not exist in the first place with the developers moving on to other things.