They want it until they're going through long periods of not winning or not being able to roll over the "lesser" teams, or they can't afford to keep up with the normal travel expenses, never mind when games are being played half way across the world because of money. A super league would be a disaster of greedy clubs caring even less about local supporters, they'd soon regret stepping away.
I also find it interesting that one of the arguments is that the tv rights should be distributed differently, with United/Liverpool receiving more of it given their reach but that tends to spin off into other clubs spending their way to the top with money not earned and it's somehow unfair. If we're making the argument about fairness then all clubs should have an equal budget they can spend each season, regardless of how much profit they're making - we know that wouldn't happen though because it's not about being fair, it's about certain teams wanting an advantage before a ball has even been kicked.