Things must have changed since I went to high school. My high school was not exactly sports crazy, and we got none of that. We had about 3500 students in our school, and when they decided to start a football team and sell season tickets, they sold 6. 
There are no academic letters in the high school my daughters went to either.
I don’t know much about what happens at sci fi conventions, but a lot of people get dressed up at anime conventions. Here are some pictures from the one anime con that I’ve been to – it’s not hard to find lots more by Googling “anime cosplay”.
Does the young woman who dresses up as Haruhi Suzumiya, or the young man who dresses up as Naruto Uzumaki, think that they are a character with magical powers? I don’t think so: they just like dressing up, and taking part in an event with lots of other like-minded people…
Yeah, but how many LARPers need to have their knees replaced by the time they’re 40? 
My experience at science fiction conventions (and I’ve been going to them for about thirty years) is that perhaps 10% of the people who go to them ever dress up in costumes.
Sir Rhosis writes:
> Sports fan outnumber science fiction fans by probably a few hundred thousand
> to one.
A proportion of more than 100,000 to 1 is obviously wrong. If there were only 5,000 science fiction fans in the U.S. (and I’ve been to conventions with more than 5,000 fans), that would say that there are 500,000,000 sports fans in the U.S., and that’s more than the total population. 200 to 1 might just possibly be true. If there are 5,000,000 hardcore sports fans in the U.S., that would say that there are 25,000 hardcore science fiction fans. Also, note that this is comparing apples and oranges. It’s measuring the fans of all sports with the fans of just science fiction. There are many sports out there, and their fans can be considered separate groups. There are many kinds of literature and movies and TV shows out there, and their fans can be considered separate groups.
Just for the record, what percentage looked like this? 
None of them.
My town has a subdivision which advertises itself as “a golfing community”. The cheaper houses are a short drive from the golf course. The more expensive houses are within walking distance of the clubhouse. Some parts of town have jogging paths and bike paths; this subdivision has golf-cart lanes.
And people think D&D players are obsessive? I don’t plan on spending my retirement playing the same 18 modules over and over again.
The answer to the OP is in the picture of the guy in the Thundercats costume in your link.
Some people, however, are just freaks of the worst kind.
Not only that, but golf is the traditional home of the Rich White Man. If you want money, power, and prestige, that’s where it lies. If the Rich White Man decided to start wearing chain mail and kicking ass in the forest, we’d have a new Tiger Woods.
That was certainly true when I first started going in the 80s, but I haven’t seen a hall costume (i.e., one not connected with a formal masquerade) in years.
Further, the type of costumes you see in masquerades are hand made and show incredible workmanship. Only about a third of them involve media costumes, and hardly ever have anything to do with Star Trek or Star Wars.
My eyes! Ze goggles zey do nothing!
The Geek Hierarchy (Abridged version – scroll down for the unabridged)
Unfortunately, cheeseheads are not mentioned. I’d fit them somewhere between “Trekkies Who Speak Klingon” and “Trekkies Who Get Married in Klingon Garb”.