What Other People Think
Taming the Mammoth: Why You Should Stop Caring What Other People Think by Tim Urban.
Continuing a sub-theme of transitioning from individual contributor to leader. As a software engineer, you can often reduce your critical relationships to a small handful. Two or three people with whom you prioritize caring what they think. Maybe they're your manager, an influential peer and an architect.
Once you hit leadership, that simple view of the world goes out the window. In a maturing org you might have twenty to thirty people you need to keep up with. At least a few of them are going to be mad at you all the time. If you're not used to that, and you care too much about what other people think? It'll eat you alive.