I don't even like Mayweather but you can't deny that he, along with Pacquiao, are far more well-known athletes on a worldwide basis than even the current UFC world champions. The UFC is just seems to be even barely growing in popularity in the UK. You can bring up Ronda Rousey and create these stupid man (Mayweather) vs woman (Rousey) fight debates all you want but she seems to be only highly well known in America.
I used to be a very huge UFC follower until it turned into the Ronda Rousey and Connor McGregor Show with reports and posts on FB pages talking only about these two particular MMA fighters. However, that doesn't mean I'll stop watching MMA fights. I just won't watch the UFC and Bellator fights in particular.
Even Mayweather seems to be trying to stay out of this stupid publicity stunt pulled by the UFC, especially by Ronda Rousey and Dana White ( https://www.foxsports.com/ufc/story/floyd-mayweather-ufc-mma-ronda-rousey-dana-white-100-million-business-081015?cmpid=tsmtw:fscom:ufconfox )