Staying at home because you're actively trying to avoid dealing with social situations means you're psychologically under-developed, and has nothing to do with intro/extroversion
edit: to expand slightly, introverts are just as capable of being gregarious, having fun at a party, etc as any other person. They'll just not gain energy from those activities and will need to do other types of activity to gain that energy back.
Not liking a lot of people also has nothing to do with introversion at all, just so happens there's a lot of introverts out there who never practice the things they're bad at and equate their failings with something innate in who they are. A friend of mine basically never comes out to any events whatsoever because he's too anxious every time about meeting new people or going into unknown situations. He says "it's because I'm introverted", as if being introverted means you're automatically sentenced to being bad at social things or you *must* be a quiet/shy person.