In the worst case? A startup already have developers, now. Don't forget how hard is to hire.
Plus, a lot of custom work in software is not sophisticated. Customer mainly have basic needs (from the POV of software development) but many of them, in disorder.
Working for them, is more about have patience ("pls move this 1cm to the left, not right, can you also do X?, no we decide after all don't do that" etc) than the kind of "raw skills" of a uber-developer.
Plus, a lot of custom work in software is not sophisticated. Customer mainly have basic needs (from the POV of software development) but many of them, in disorder.
Working for them, is more about have patience ("pls move this 1cm to the left, not right, can you also do X?, no we decide after all don't do that" etc) than the kind of "raw skills" of a uber-developer.