To the OP: Can I ask what your process was? A project like this obviously takes a lot of time. How certain were you that you had a product people wanted before embarking on the dev?
I've also worked at companies where we built something similar in-house. So while this is a very niche product, I know there's a least a few developers out there who may find it useful.
Building something like this is also a great way to find new problems to solve. I think even if it's a niche idea or something you're not sure about, it's better to start building something than to wait for the perfect idea.