I have been working on a casino market - a very indirect to the niche but casino market and it's very profitable. My entire network of Web2.0s is dominated with AI content, which you can build 100% free and index with tier 2 and tier 3 links. I had no luck with purchasing backlinks, and since you're planning to work on para sites, there's no point, as you have a much stronger and safer way to do it. Just build backlinks yourself - you can simply do a 2 or 3 tier link wheel blast that connects each tier, and automate the entire process with GSA or Ranker X or using both... Those two were much better than seo neo or money robot (but my backlink profile also got money robot links) I mostly focus on consistent content and backlinks than other facts as relavency, which means I make sure all my tier 1 links are live and I'm not sending all the tier 2 backlinks to dead tier 1 links. That's the only thing you have to watch out for if you go with tiered link building strategies. Para sites may take some time to get indexed, but once they're indexed, they'll index more and more. Just make sure to interlink all the posts well. There are a lot of posts on this - just use search. I normally don't care about niche relevancy backlinks at all, as they're nearly impossible to get in the niche I'm working on.