I lived overseas for a time in an area that didn't use English. I loved it, enjoyed being there, but one day I noticed that I was talking to myself! At first, it was just exclamations out loud (quietly) when something happened around me. It progressed to me describing or evaluating my meal, a book, a scene I was looking at. I realized it when I noticed ppl looking at me strangely (they normally did anyway), and as I looked back wondering why they were looking at me, it hit! I had been talking out loud to myself, normal volume! Why? I figure it was loneliness; but loneliness for hearing English. I was the only one who could speak it! And then it hit me again, a new found epiphany about all those "crazy homeless" ppl who I'd seen back home, muttering to themselves as they wander around. What if, instead of (or in addition to) being mentally unwell, they were just lonely, and having no one to talk to led to them talking to themselves? Whoa.

The few interactions that I've had with homeless people gave me an impression that the thing they needed the most was human interaction. They'd be thankful if they received a meal, but they'd start talking in a way that made me think that what they needed the most was for someone to listen to them or some human interaction. It didn't seem like many people would ever stick around for more than a few seconds.

I'm talking about a very small sample size here, but still.

"I used to think that the worst thing in life was to end up alone. It's not. The worst thing in life is to end up with people who make you feel alone." - Robin Williams

One study found that lonely people also engage in more imaginary conversations than those who don't consider themselves lonely. Perhaps ending up talking to oneself out loud is somehow related?

https://psychnewsdaily.com/lonely-people-have-a-unique-brain...

That is surreal! Like one step away from “The Sixth Sense” movie

Language is so tied to our sense of connection and belonging