Yeah, don't go to events like that. Don't even come up with an excuse. If asked why, just say that parties aren't your thing. That should be enough of an explanation. If it's not, that's there problem.

And it only seems like an extroverted world because they are noisier and create more drama. There are plenty of introverts about if you know where to look - libraries, museums, art galleries, peaceful woodlands. In my experience, there are plenty of people enjoying quieter things. They're just not making a big song and dance about it to draw attention to themselves.