I think if your heart is in it and you truly are passionate about your niche, you will be rewarded with a great community and quality content creators.
My wife has a reasonably popular instagram for vegan recipes and I am speaking with her about using her connections in that community to start a niche of our own that we could 'manage'.
I have a passion for basketball, gardening and nutrition and a good friend of mine is very knowledgeable in the automotive industry.
I'm really excited by this project (as you can probably tell), and am so glad I found it when I did!
I too am worried about the auction process but also understand it's necessity. I do wonder if there's some kind of incentive for the original idea, if the person with the original idea doesn't end up securing the niche????
EDIT: Is there a possibility of adding a "sub-niche"? E.g. NBA main niche, NBA Draft would be a sub-niche?