Think about it....Tobi's plan is to control everyone with his eye of the moon and essentially finally create peace. In his eyes this is the only way to create PEACE. The members of akatsuki wouldn't be willing to risks their lives for no cause....they are fighting for peace because of the damage war has done to their lives. Look at Sasori for example.....his parents were killed during war therefor entirely ruining his life. He wasn't happy without his parents and doesn't want anyone else to go through what he did....so he joins akatsuki in order to help tobi's plan. Yeah the shinobi alliance was created in order to defeat tobi but think of how many years shinobi and conflict has existed....you really think this alliance is going to last? Im new at this so lemme know what you guys think