Every sport is going to have those types of people. It just happens to be, MMA is watched mostly at bars. Those douchebros are the same douchebros causing problems at Football and Hockey games.
Nah. I'm a season ticket holder at our local football team and as you know I regularly go to Senators games, they're nowhere to be seen (except when the Leafs are in town). This is very much a UFC thing.
Edit: it is of course possible that all the douchebros love hockey and football just as much, but I don't notice them because the crowd is sufficiently diluted by normal, pleasant, non-douche sports fans. Therefore, it might be more accurate to say that the big problem with MMA is that it's a sport that only douchebros like, and thus the douchebro-ness goes unchecked by the presence of non-douches.