Exterminators of all types, people who manufacture roach control products, and those people who are responsible for making a house as inaccessible to bugs as possible. I wouldn't be surprised if there are others, but that's what comes to mind.
I have assume that this question comes as a result of reading my article, "The Cockroach Factor". If it is approached from the standpoint that it was presented, your question would raise the issue of what happens when the "ignorance of the voter" is eradicated as that is the effect cited in this article? It's not about a given group of people but more of a cross-section of educated Americans who seemed to be removed from the issues but still vote. American suffers an "infestation" of that as such. Cockroaches like the "less than informed" voter do not represent anything productive, thus I would conclude that there is no "money" to be made in the process. In the insect world, if the cockroaches suddenly die, the exterminator loses money. If America has an infestation of voter ignorance, then if that dies not out, the "teacher" loses money as a result. The focus here is on "infestation" not productive use if that makes sense to you. Thanks for asking. WB