No. What people THINK is nerd culture is mainstream culture.
Shows like 'the big bang theory' are mainstream and have such a 'hello fellow kids' vibe it makes my skin crawl.
No, I don't think so. I think outright nerd culture is mainstream culture, and I say this as someone who can remember playing 2nd edition when I was very young and well before it was mainstream. I played with a kid from a catholic school and if he had been found out, he would have been made an outcast there. I actually got to witness priests telling people that this dungeons and dragons stuff was satanic firsthand. Everything about nerd culture is far more mainstream than it used to be and the world is far better for it. I mean you give "The Big Bang Theory" as an example, as if it isn't entirely mainstream to make fun of that show in the first place. It is both mainstream to watch it and to make fun of it. Being "mainstream" isn't one monolithic thing. Being non-mainstream meant being actively ostracized in some way for what you enjoyed. And the vast majority of things that were once considered "nerdy" enough to be worthy of ostracism, in the vast majority of places, are now utterly normal and banal to enjoy.