If our life was a video game, the default mode for our lives would be single-player.
We see the world from our eyes; everything that happens to us is incredibly important. Everything that happens to everyone else we need to understand via some mode of communication, and therefore it can never be as immediate or important as what's happening to us.
Naval reminds us:
"The reality is life is a single-player game. You're born alone. You're going to die alone. All of your interpretations are alone. All your memories are alone. You're gone in three generations and nobody cares. Before you showed up, nobody cared. It's all single-player."
But life isn't really a single-player game; if it was, it would stop being fun and stop mattering pretty quick.
If life was only a single-player game, then by definition, we shouldn't give a shit about what happens to the other NPCs (nonplayable characters) in our lives—NPCs like our families, kids, or friends. But we do care about all those characters we don't control.
Heck, I've got two daughters, and I will tell you that I care more about them than myself. I am not unique; most parents feel this way about their kids. If this were a single-player game, most parents would be doing pretty badly right now in terms of the score.
But I think life is actually a multiplayer game. Everyone in it is alive and thinking, and no one is an NPC. But the people that go through it like a single-player game do indeed die alone. It's tough to blame those people though, the default setting for life that most people hit start on and never get out of is, in fact, single-player.
It takes a lot of conscious thought and effort to get out of that default mode. It takes effort to put other people first. But if we can get out of that default mode, the whole game is more meaningful and fun. Then the score and the whole thing start to matter.