The “comic” conventions don’t even have comic books for sale these days. They are dominated by adults in trick or treat costumes, getting the autographs of the actors who portrayed the characters in the MOVIES and TV shows based on books and comics.
This “nerd chic” is a hipster marketing plan, it isn’t genuine fandom.
There are layers to it. A big part of it is Hollywood figuring out how to make good superhero movies, there’s a good chunk of the people out there that will just plain watch a good movie and they aren’t concerned with the source material. But it did establish these character as significant pop cultural icons.
Previous to that was JMS changing the nature of comic book conventions. The cons were starting to have problems because comic sales had dropped dramatically form the boom boom 80s and they were desperate for a way to stay relevant (read: fill these large hotels they were renting). Meanwhile JMS had this pilot he’d made that he was desperately shopping, desperate enough to cold call any nerd related convention he could get to and beg for 2 hours to show the attendees Babylon 5. At San Diego ComiCon he made all the right connections, and of course he’d developed a lot of goodwill in the fan base, and he continued to grow that goodwill by bringing previews of every season of B5 to SDCC. That was the seed that turned CCs in general and SDCC in specific into the “must promote” place they are today.
It’s genuine fandom as far as I can see. People spend hours working on costumes, hundreds to attend the con, and hours more to get that autograph. Sure maybe they’re “just” fans of the movies and not the books, but they’re still fans, they’re still dedicated, they’re still kind of nuts. And they’re making some of the favorite people of old nerds filthy rich. One of my favorite parts of The Walking Dead TV show is seeing Greg Nicotero (long one of my favorite people in the world) finally getting recognized by people who aren’t hardcore horror dorks, and the fact that most of the people who recognize him now have never seen Day of the Dead of Phantasm II doesn’t bother me. I just think it’s cool that I can now mention him in “mixed” (non-nerd) company and people know who I’m talking about.