reducing fear when cycling?

Perhaps this is the problem. I notice them all, all the time, every time, and they make me really depressed and angry :(

This. I look around so much, I swear I look like I've got a nervous tick.

I'm astounded by how many cyclists I see who never look behind them, even when changing lanes, or filtering and often with earphones in so not even relying on sound. Assholes.