The fact that he would go out of his way to help someone else just means he's not totally lost. I hear what you're saying but the fact he still has the capacity to help others shows that he at least has a good heart somewhere in his chest cavity.
As for why he will allow himself to do good things for others and not for you or your family, I can only guess that perhaps there are no strings attached with the former? Or maybe he feels the stranger would be more likely to show appreciation that he thinks he doesn't get? Yes, it is very maddening, but obviously he hasn't quite figured out his own mind yet or put things into proper perspective. I think there are a lot of anger and self-protective rationalizations behind his ignoring your pleas. He's probably at a point where he's thinking, right or wrongly, that his own family doesn't appreciate him, so he'll be more likely to put his energies in helping strangers. He's locked into me, me, me and he can't see the alternative because he thinks you and everyone else is out for themselves. Maybe?
Again, I really don't know. That's why I really think therapy is in dire need for him.
