MyTeam contracts price differently for each tier of player. You will spend more MT points with a loaded team.
Gold player contracts are valued at 60 MT per game so that's a cost of 750 MT if your entire lineup is Gold (600 if only top 10 are gold). That's about how many points you generate per game, so those players aren't generating any MT over the long-run. The only way they could is if they have excess contract cards from all the real life money they spent on VC to buy packs.