The waning of traditional sports partially fueled the rise of UFC. It is simply more interesting than boxing or baseball.
I want to point out that this is not true, and
not why the UFC is a success today, and if you dont believe me, just ask yourself why the UFC is the only MMA organization you know/care about, and then go read about the history of the UFC and how it came very close to disappearing forever. UFC became the juggernaut it is today thanks largely to marketing, advertising deals and The Ultimate Fighter, and at the final hour no less. The UFC is a success because they focused on all the things most combat sports
dont focus on.
Many many many combat sports investments have been tried on the basis of "well clearly, its more interesting than boxing because more things going on!" and have been stunning failures. I mean literally everything you can think of that could be involved in a combat sport. From simply trying to introduce to americans and europeans to sports already established elsewhere in the world (muay thai for example, which is fairly popular in europe, but sunk like the titanic in the US) to absolutely ridiculous high concept stuff. Its all been tried, especially during the 80s and 90s, and most of it was over before it ever really began.
Finally, the perception that the UFC is more popular than boxing these days is certainly a popular perception, but its not actually true. Between the years of 2002 and 2017, boxing had the biggest PPV buy rates 13 out of 16 years and boxing owns all 8 of the top 8 combat sports ppv buy rates of all time. Boxing is definitely badly managed, sprawling, and hard for the casual fan to follow, but it remains the premier combat sport in the entire world, and thats
why it can afford to pay its top athletes multi million purses, including guys you dont know by name. By contrast, theres only ONE guy in the UFC able to demand anything close to those purses.
Finally, an article that makes the case it is the UFC that will be experiencing struggles to maintain market share in the coming years, not boxing. Take with a fistful of salt, but it does make some salient points and cites some interesting figures
https://www.thestar.com/sports/2018/02/15/ufc-isnt-killing-boxing-its-using-boxing-to-survive.html#:~:text=Contrary to public perception, boxing,49-year-old demographic.&text=“That's unprecedented in all of,20 years as a manager.