Naw. Most are just kidding around and/or saying outrageous stuff in the off chance that he turns out to be a world beater so they can claim to be prophetic geniuses.
The most annoying mega fans out there, in my experience, belong(ed) to Anderson. And I'm speaking as a big fan myself.
The myth that Anderson simply was never in any danger of losing any fight got pretty outrageous... and then when grew to the point that things like the first Chael fight got explained away as Anderson letting Chael beat on him for 4.5 rounds so he could add to the drama and finish him by sub, it was downright sickening.
There are still some out there, BTW, who refuse to believe that Weidman beating Anderson twice in a row means anything at all and who argue that even the fact that Anderson was losing or even in both of those fights up until the finishes is meaningless because Anderson's been behind in fights before and won so, therefore, he would definately and certainly have come from behind to beat Weidman if not for those 'flukey' things happening.
In general, though, fans don't bother me as much as haters. Guys who live on Sherdog to bash JJ or GSP or Fedor or Silva are some of the most obnoxious individuals I have come across anywhere in my entire life.