The other problem is that the AI crowd seems to be assuming that people who might exist in the future should be counted equally to people who definitely exist today. That's by no means an obvious position, and tons of philosophers dispute it. Among other things, it implies what's known as the Repugnant Conclusion: the idea that the world should keep increasing its population until the absolutely maximum number of humans are alive, living lives that are just barely worth living. But if you say that people who only might exist count less than people who really do or really will exist, you avoid that conclusion, and the case for caring only about the far future becomes considerably weaker