I don't understand, who are the people profiting from click fraud on Facebook? Obviously Facebook is but we can pretty safely presume they're not coding bots on

I don't understand, who are the people profiting from click fraud on Facebook? Obviously Facebook is but we can pretty safely presume they're not coding bots on their own ad network. A competitor could maybe profit from it but this seems like a rather roundabout way to damage your competitors. What other rational business case is there to build click bots on Facebook? This is not like Google with AdSense where they pay out 3rd parties, the motivation there is clear.