Imagine someone at another company reads your site, and it informs a strategic decision they make at the company to make money around the niche activity you're talking about. And they make lots of money they wouldn't have otherwise. That's totally legal and totally ethical as well.
The reality is, if you do hard work and make the results public, well you've made them public. People and corporations are free to profit off the facts you've made public, and they should be. There are certain limited copyright protections (they can't sell large swathes of your words verbatim), but that's all.
So the idea that you don't want companies to profit from your hard work is unreasonable, if you make it public. If you don't want that to happen, don't make anything public.