The sport of MMA is fairly new, dating back less than three decades. It had to fight through a lot of negative perceptions, particularly from top politicians who deemed the sport as 'human cockfighting'.
The sport had to undergo changes and get unified rules before the perception started to change. Before that, boxing was the big combat sport, having far lesser negativity attached to it and constantly selling out arenas.
MMA had to undergo an evolution but its popularity growth has been remarkable. It's grown among the average person, and over the last decade or so, an increasing number of celebrities have begun to view MMA (or just UFC) and have also become big fans in the process.
Apart from just superstars such as The Rock, or United States President Donald Trump, here are a bunch of other celebrities who you may not realize are big MMA fans!