While those are good reasons, I suggest that the biggest reason is simply that present-me cares about “me”. And “me” is a temporally extended person who includes future-me. There doesn’t seem to be anything particularly irrational about self-concern, any more than there is anything irrational about being a Red Wings fan if you happen to live in Detroit. (Or particularly rational, for that matter.)
While those are good reasons, I suggest that the biggest reason is simply that present-me cares about “me”. And “me” is a temporally extended person who includes future-me. There doesn’t seem to be anything particularly irrational about self-concern, any more than there is anything irrational about being a Red Wings fan if you happen to live in Detroit. (Or particularly rational, for that matter.)