I try not to overthink it - if it’s a topic I’m interested in I just keep posting, even if I’m alone. There’s no point (in my mind) in worrying about people being put off of a community with a single poster since the only alternative is a completely dead one. It might be just me but I feel like the latter is less inviting - if only because you have no idea if anything you post will get a response. With a single poster you know there’s at least one person passionate enough about the topic to engage with you.