Well you're not a monster
But it does sound like you might be private in social situations. It's a social energy kind of thing; some people feed off the energy of others while other people have to give their energy out.
Take the Webgoji for example. Extroverts love to feed off me like vampires. Once we say "nice weather", I'll start coaxing them into talking about that weather. What's nice about it compared to last week or whatnot. Or better, instead of just "hello", I say, "How ha doin'?" genuinely interested in how they're doing. People like to talk about their day and I think it makes them feel good to have someone care for just those few minutes.
Once I get to know someone through asking how they're doing or "how was your weekend? Catch any shows?", then I can get to know what they do with their time; movies, skateboarding, whatnot. Then I can ask more specific questions.
Overall, just showing a curiosity and interest in other people helps me. I don't have many close friends, but pretty much everyone likes the Webgoji so give it a shot. Ask specific questions and show that interest in others and they may start to open up.
(Psst ... and being private ain't all that bad. Your energy is yours and people can be exhausting.

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