I’m not going to blame this on insecurity, but I think ego is a bit more accurate. I was working under a senior software engineer in maybe his 50’s in my first real job out of college. A big part of our time went to maintaining a build system that was fairly large, maybe on the order of tens of thousands of lines of Ant code.
The bone that I have to pick looking back is that I got the blame when I had trouble organizing myself. Our team didn’t use any sort of issue tracker. There was absolutely zero collaboration tools beyond verbally issued instructions in meetings and email. Looking back, I realize it was madness. As an experienced developer, my manager should have had known that an issue tracker would be a high priority. Yet instead I was blamed.