I see no evidence in The Kite Runner that Rahim made any of his decisions for his own benefit. He seems to act as the moral conscience of the novel: a genuinely thoughtful and caring man. Though he loves Baba, he also loves Amir; but unlike Baba, Rahim accepts Amir for who he is, along with all of his shortcomings. When Rahim moves into Baba's home following his departure to America, he does so in order to maintain the home--not to live in more luxurious surroundings. Rahim seeks out Hassan and invites him back to Baba's home because he knows that Baba would approve of his helping his old friend's son (who is actually Baba's son, which Rahim knows). When Rahim sends for Amir and then reveals the secrets that Baba has kept from his son, Rahim does so because he knows that the information is necessary for Amir to better understand his late father; and because he realizes (as Amir comes to see) that retrieving Sohrab is the only chance for Amir to atone for his past misdeeds.