Yeah, I can't do parties or large get-togethers for too long without feeling like I'm wasting my time. Close friends or family on a holiday is fine though.
Part of it is social anxiety, and another part of it is just not seeing the use of it from a long-term perspective. No genuine bonds are being formed or strengthened, I'm not actually enjoying this, nothing's being gained, none of this matters. It's pointless self-indulgence. A distraction. I could be working on my resume, applying for jobs, finishing the book I'm reading, catching up on my homework, etc.