Who needs custom software development?
The owner of the company has a fanatical or egotistical side. He or she likes to have their software their way. He or she clearly understands their business from a micro and a macro level. He or she wouldn't mind having a showpiece to brag about to their competitors, fellow business owners or friends. If it makes the business run more smoothly, i.e. exactly how they want it to run, the investment in custom software will pay for itself.
They need a software developer who can work with, and has worked with, demanding clients. They need a software developer who can accept criticism, even when they might be right. They need a software developer with equally high standards about the quality of their own work.
This company wants perfection and hopefully, I can share in the satisfaction from reaching such a lofty goal.