I wanted to share with you an anecdote from Jerry Holkins at Penny Arcade:
I received the strangest question in an interview once: somebody wanted to talk to me about MC Frontalot, who coincidentally has a new album out. They wanted to know why rap about nerd things, or make comics about nerd things…. I scrunched my whole face up, and the region between my eyebrows shifted tectonically from plain to mountain. But he could not see this, so I was forced to express my confusion with the human words.
This was a person writing an article for a newspaper, a device which transmits culture, but he didn’t seem to understand what he was doing! Maybe he was confused because he was taught to “speak†without “voice,†that is, to communicate neutrally. Maybe he found the printing press in the woods, and operates it via dimly understood rituals. But here’s the apparently impenetrable math: people create culture. And they create it by describing the world in terms which are relevant to them. Who does he think makes all this stuff?
All that changed was the hand on the tiller.
I find myself having a similar conversation quite a bit. I try not to hold it against people who don’t understand, though. It’s not always obvious to outsiders why the whole “nerd” thing would remain relevant to us into adulthood. I guess that’s why I wrote a dissertation trying to explain it.
Geek Studies 
And what do you tell them? I can’t say I entirely understand it myself.
Generally I stammer a bit and give an answer that feels unsatisfying, then think of a better answer later, after the conversation is over. Still working on that.
… Oh, all right, here’s a real answer: I give a much longer version of “because people create culture out of what is relevant to them.” Then I talk about how I went about writing my dissertation until they either nod politely to signal I can stop talking now, or chime in themselves because they actually start to get it, even if they had no idea that geek culture is a thing at all. It is rewarding to hear fellow geeks indicating that this is something worth talking about, but it’s also really nice to get a receptive reaction from open-minded people who sense this phenomenon and want to understand it better.