"They're all dead, or they're going to be. It's so... stupid. I... I mean there's..."

There's people in other worlds, but it's not his own, and he can't run away to other worlds forever. They have their own lives, ones that don't involve him, and it's not like he could impose on them forever. He has a mission, he has a goal, he wants to help other people, but...

"... I have to do as much as I can. I don't... if I don't, no one will." Maybe he can't save the entire world, but he can save other people from horrible situations. That, at least, he can do.