That's only if the company doesn't know how to run a software project. Most of the value extracted from software is in the maintenance phase, not the developme

That's only if the company doesn't know how to run a software project. Most of the value extracted from software is in the maintenance phase, not the development phase. When the principal developer on a successful project leaves, it multiplies the time and effort involved in maintaining the code, and then what happens? No one does the maintenance, and two years later the new team decides to rewrite it. Sunk cost fallacy is not a fallacy when you're talking about years of fully tested work lost, and you can't even find people who know what the requirements were.