It's easy to forget that 'user' or 'persona' is just a tool for the UX design process. It's a generalized reflection of human behaviors in a specific context. However, there is still a considerable gap between those in the way we understand users in our every workday and users in reality.
I almost exclusively read non-design-related books because nothing has been helping me become a better designer than learning about diverse perspectives and insights on the human being. Realize how 'human,' not 'user,' would experience, feel, think, and live through the technological world we live in and work for.