I think it hasn't really hit me yet because I always vaguely assume everyone who likes popular stuff is just operating on some sophisticated ironic meta-level I don't understand.
Just recently though it occurred to me that there might be people who actually LIKE dubstep, or whatever that monotonous autotuned crap you hear everywhere these days is called, and not as in "yes, I grimly resolve to enjoy this in order to try to fool myself and others into believing that I don't take myself too seriously, that I appreciate there's a level of craft that goes into the production of even loathesome cultural products and that different things are appropriate to different social situations", but as in THAT IS THE MUSIC THAT THEY LIKE, as if it were Talking Heads or something. It was a truly terrifying thought and I didn't get any sleep that night.