As long as there are fans that are willing to pay this exhibition match, it will continue. The Paul Brothers and Floyd Mayweather are making huge money. Even those former boxers and MMA fighters as well.
That's true, only the fans can stop this madness because without the fans they will not make money. It's robbing the real boxing fight because the revenue might be split or it won't be able to maximize the profit of the professional fights, but it's not the fault of the promoters of exhibition fights because boxing whether it's professional or exhibition still belongs to entertainment.