>most people today have headphones on all the time. I don't understand it. I'm not sure, but it would seem people hate their own voice?

I can't generalize for everyone and maybe some of those people you observe are just listening to music all day long.

In my circle, we have earphones all the time because we're listening to podcasts of news, tech industry commentary, macroeconomics and finance, etc. If one is working in an area where you're professionally rewarded by being curious about the changing world and being "plugged in", having "headphones on all the time" can help with staying up-to-date. Even with all that headphone time, there are still many hours in the day in personal silence. Laying in bed consolidating various thoughts before falling asleep. Standing in the shower. Reading blogs, etc. Before podcasts, we'd have to "waste time" sitting in front of the computer to catch up on the same material. Podcasts help us multitask.

Of course, not everybody needs (or wants) to have headphones on all the time. The mathematician Andrew Wiles pursued Fermat's Last Theorem for 30 years before finally solving it. He doesn't need a random podcast that talks about the Iran war and its downstream economic effects on manufacturing computer chips. That type of "useless" news would probably bore him.

>, even driving. In fact, I think my problem is the opposite: I just can't do two things at once. If I'm listening to something, then I can't be doing anything else.

It just depends on the threshold of mindless activity. If I'm driving in an unknown city with confusing one-way streets, I don't want a podcast voice yapping in my ear while I'm concentrating on reading the traffic signs. On the other hand, driving through 100 miles of monotonous corn fields on a highway means I can catch up on a backlog of podcasts.