It is not really, though. Sunk cost assumes that time or money spent does not change your state as an economic agent and only adds material possessions.
You don’t know what will work in the long run because you have never done this in the long run. However, there is certain value of expertise - if you spent a month integrating a component into a system, you have intimate knowledge of that component that you will have to re-acquire if you install something brand new.
Indeed, and that's kind of why I'm erring on the side of remaining with my expertise. My experience with my own systems is that when they are an extension of myself, I am more productive than teams of people (this was a feedback I received while working at the hedge fund - they fired my entire team and got me to do everything)
