What I don't get is why you identify so much with the characters on the show as to define them as analogous to "you" when jokes are made at their expense. Sit-com characters are always exaggerated caricatures designed to elicit humour. They're not laughing "at you"; they're laughing "at Sheldon" (or whoever happens to the butt of the joke at the time).
Taking the humour to heart as a personal slight seems like over-reading the intent of the gags, as well as giving too little credit to the ability of most people around you to separate reality from fiction. In any event, they not even that insulting; generally, they're pretty mild pokes with some nuance.
In terms of influencing any sort of national or global perception of what SF-fans are like, then again, this only matters if someone is as extreme, narrow and socially-inept as the characters in the show. Assuming you have a more balanced life, it isn't going to make the blindest bit of difference how someone views you or indeed affect you in any sort of way. So I can't say that I see the practical problem.
I don't write the above to in any way suggest that you don't have the right to have your opinion; of course you do. But I think it's a shame in terms of your missing out on a few good gags and funny situations.
I meant to post this earlier cause I was already thinking about it, but yes, I get that it's a TV show. I get that they're caricatures. And folks can laugh at themselves, but like I said: this show is not laughing "with us at ourselves", it's laughing "at us while we laugh at ourselves". It's a crucial difference that I'm having trouble putting into words.
I guess my problem is the adoration it seems to get, as opposed to, say, a grudging respect for something like this pointing out our sillier aspects. It just seems far too mean to be taken as "friendly ribbing", more like the jock in the room giving you what he thinks is a lighthearted ribbing, but is in truth killing you on the inside, but you put on a brave face and laugh along because he's not shoving you into a locker.
I think I'm at risk of going round in circles but I'll try to explain my perspective once more as well, because currently it seems we're talking at cross-purposes to each other.
I know you "get", on a literal level, that this is a fictional TV show. But on an emotional level, you're still equating/identifying yourself with the characters enough to perceive the humour poked at their lives as being directed at you, and on a par with some sort of bullying. Beyond the fact that the characters like science fiction, I just can't see enough of me in them to view anything that happens to them as being in any way laughing at (or, for that matter, with) me. They too obviously caricatures for me to feel any emotional bond with them in that way.
Put it this way, I felt more of an emotional resonance with, say, Monica, Chandler, Frasier or Niles than I do with Leonard or Sheldon.
(The lack of any real emotional resonance is, incidentally, is why I don't rank BBT as one of the best sitcoms I've seen, just ranking it as pretty consistently funny.)
Anyway, hope that explains where I'm coming from, at least.
