I would like to say that I'd totally go up to her, but there's no way I'd have the guts. What's the point of chatting up someone wayyy out of your league, right? She would've forgotten me 5 minutes later.
And if it was a celebrity-fan interaction it would be even worse. You'd be one of a billion. Less than a face in a crowd. She'd just smile and nod and say a polite thank you for supporting her and that would be it. You wouldn't even be a person to her, just another fan. A drone.
tl;dr I'm a beta faggot