Because it's important that they're actually real.

Yes! I think that's a lot like what I was talking about.

You will eventually become the person you are in the future

Present-you won't. Present-you will go away and never know that will happen. You-over-time may change from present-you to you-to-come, but I wasn't talking about you-over-time.

Also, mind reading could change this some day, maybe.

How would you actually change yourself? It's very difficult in practice.

Yes, but even if it weren't possible at all, and we thought it were possible, whether we wished for it could say a lot about what we really want.

People send less money to people in developing countries than say, war veterans or people at home.

Yes, but that's very different from saying that people don't care about far away people at all except in so far as they get changed by them. If it were completely easy for you to in a flash make the lives of everyone you'll never know about ten times as good, for free, you would want to do that.