As someone who grew up being very shy, I can tell you that For one, making friends is very difficult when you're too shy to go up to people so people just assume that you are rude/'antisocial'/think you're too good
If you want to get involved we run a shy to social in 27 days Facebook group every month. Get started with people who know what you're going through: https://www.facebook.com/groups/2116201065290877/