But you name the most difficult niches too.
It starts with a passion. Where does your passion lay? Then it starts with an audience. Do you know people that would follow you in this niche? Do you have some expertise and experience to offer? Do you have some power users to help you kickstart your project? If not, it’s probably too soon to launch your project.
But assume that you do, do you have a strategy for growth, and more importantly organic growth? Is there competition? What can you offer differently than your competition? What are you willing to invest (time/money)?
These are some serious questions that help you forward in your community’s life and expectations.