They've been bugging you to join them for a while now because you have the most potential to help Earth and save human lives. However, for some reason, you don't want to join the Justic3 Leagu3, no matter how much they pressure you to do so. You could care less about earth and those morally speeches, "Just tell us why," Super|man says. He's seen you save people, not knowing you do those for your own benefits, so your refusal is confusing to him and the other members of the league. It's not like you can just tell them why, either. Who has time for their judgments.