>Programmers aren't immune from overestimating their competency
I would actually phrase it differently: programmers quite often overestimate their competency. I am not sure if it is unique to programmers or just an instance of the general inability to objectively analyze ourselves, but I do notice that the vast majority of programmers I have met (myself included :)) have a tendency to consider ourselves a smidge more capable than we actually may be from a purely objective standpoint. Then again the stretching is what grows great developers, so that overestimation that spurs you into attempting things just outside your current grasp is probably a net positive.
The reason is because the skill appears as magic to others, whereas business skills are something that anyone can at least imagine themselves doing. This is completely orthogonal from how difficult these jobs may be under varying circumstances.
I would actually phrase it differently: programmers quite often overestimate their competency. I am not sure if it is unique to programmers or just an instance of the general inability to objectively analyze ourselves, but I do notice that the vast majority of programmers I have met (myself included :)) have a tendency to consider ourselves a smidge more capable than we actually may be from a purely objective standpoint. Then again the stretching is what grows great developers, so that overestimation that spurs you into attempting things just outside your current grasp is probably a net positive.