But it is, like so many of these things, a skill. You have to practice it.

I think that putting earbuds in and checking out of the world around you is a really awful thing to do as your default in life. As a "sometimes" thing it's fine, even healthy. There's a lot of talk of public transit in this thread. If people do it during riding transit, and not really at other times, I'm fine with that. But so many people have their earbuds in before they leave their front door, every day, every week, and they don't come back out.

And I think that's really, really unhealthy, for them and for the rest of us.