I think people are stupid in general and prone to pidgeonholing others in whatever way they feel like at the moment. Being an introvert or extrovert are just the tip of the iceberg for the true dynamics of what either characteristic brings to the table. So what if they say that? You will just alienate more people if you're hostile about their lack of knowledge.
It's true though, people who are gregarious and outgoing attract more attention. But, who cares? You get to choose who you hang out with. You should definitely be true to yourself though.
These guys who attract lots of attention don't give a damn about anyone else, unless something makes them look good. And then it's only temporary to fight boredom. They leave a wake of unhappy people behind them. I bet you don't want to be like that.
If it's a girl you want you just have to brave it out and talk to her. I'm guessing you don't really believe that a guy is better off having all the girls swooning after him. That's just silly.

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