I was curious so I did some Googling just to get a sense if what you're claiming is true and it turns out you very likely wrong on this matter. According to TIDES/University of Central Florida, more than 80% of UFC fighters have a college degree, which is much higher than many other sports including the NFL (31%), NBA (20%), and MLB (less than 45%).
But you mentioned fans specifically, and here you're also way off. Much like the other sports I mentioned, the demographics of UFC viewers are also much more educated than the other sports I mentioned. Based on the Sports Business Journal's survey, 42% of NBA viewers have a college degree, 34% for MLB, 32% for the NFL, and 55% for UFC.
Now you can object to college being a good indicator of intelligence and that's fine, but it's probably a much better indicator than just randomly making stuff up and stereotyping people based on their hobby.