Do people in my niche have the money to pay?

I’ve chosen a niche and am committed to it 100%. I have one paying client who’s paid me $3,000 so far, so I know that there are people willing to pay me. But are there enough people willing to pay me? I’ve been hanging out in Facebook groups for insomnia, and so many of the people there are wanting to try medication and scoff at the idea of paying a coach to help the with this issue. I feel like the client I found is a fluke and that I won’t be able to recreate this success. To be fair, I haven’t been making loads of offers and I think there is fear on the part of the potential clients that they’ll pay all this money to buy yet one more thing that doesn’t work. So maybe I need to work on my offer, guarantee and the messaging.