Yes, I very introverted in high school. I went to a very rich high school as the scholarship kid and as a result, and felt I was shunned by the rest of kids unless they needed help with a subject etc. It didn't help that I was a minority in a majority white school without even money to back me up. The "shunning" except when they wanted something really made me somewhat of a bitter person towards them and I withdrew inwardly, spending a lot of my time making up that money by making websites for people in the school library on my free time. My only friends were the other nerds and we were all kinda bitter.
I didn't really like who I was and in college vowed to stop start enjoying life more as no one knew me or where I came from and there were no expectations on how I was. I became a lot more extraverted and a lot happier for it. And I also changed my views on a lot of things I used to think. I look back and realize a lot of my own insecurities were projected onto my beliefs - they weren't necessarily the truth, just how my mind colored it.
Back to high school in particular since that's what this is about - maybe some of those kids didn't shun me to the extent I believed they did* Maybe part of it was also on me because I didn't exactly give off a friendly persona and in some cases I'm sure I might have even appeared hostile and defensive. Maybe the people I hung out with had something to do with it because we were all kinda bitter. Most of those nerds have changed (and we're still friends) though a few (notably one) remains the same. It is hard for me to be around her these days as she continues to be very bitter.
*I exclude my actual bully from this, as he was totally in the wrong, but he actually apologized to me years later and I accepted.