I've always talked to myself from an early age, I think it's a coping mechanism from a fucked up childhood that's stuck with me.

The problem I've found with it is that because I hardly ever converse with anyone else, my opinion is always right because I'm always seeing and judging the world from my own inward point of view. There's no-one to contradict me or argue with because I'm talking to myself. I then get annoyed when things kind of get in my way, or don't go as I'd planned because I've obsessed over the details in my head.

More recently I caught myself actually having a conversation with myself, and I stopped and was like "....woah, this is fucked up".