Over the course of my life, I heard people use the term "cotton industry" to derogatorily refer to a group of people that make money based on something more successful. For example:
On YouTube, an entire cotton industry has sprung up around criticizing alleged "plot holes" in movies, raking in many millions of views and ad-revenue.
While writing something, I decided to double-check the expression, yet after spending some time doing extensive Google-fu, I could only find references to the history of literal cotton manufactories.
English is not my first language, and I've never actually seen the term written down and only heard people say it, and as such I'm coming to the conclusion that I might be dealing with a "damp squid" here.
Did I always mishear the term, or is it simply that I couldn't find the term? And alternatively, what would be a proper alternative term commonly used to describe this "making money of something more successful" situation ("parasites" is too dehumanizing and loaded)?