I think a part of it comes from the fact that nobody has cared about my problems, so why should I care about other people's problems? Part of it also comes from not knowing what to do about other people's issues. I've always just ran through social interaction purely logically with almost no emotion involved. "Oh, they said a joke, I should chuckle slightly to show that it was funny."
But as time went on I've found myself to be more understanding of people I guess? Not necessarily on an emotional level, but when they talk about some topic I'm able to logically understand where they're coming from even if it's something I don't agree with or have experienced. It's not quite empathy, I'd describe as detachment that let's me see things a little more "objectively" (I hate to say objectively since I don't get to decide what's objective). Maybe it's more of the logical robot component kicking in.
Sometimes though, I just feel that everything is so unimportant that there isn't a point to care. We have almost no power to change the world around us, or to change other people, and because we don't I don't see a purpose in getting worked up over anything since I can't do anything about it anyways.