Why are some very smart people so quiet?Watch
Not saying I'm very smart, I am also not remotely shy, but I didn't want to be judged by everyone else for prioritising grades so much
By the time sixth form rolled around I was very not quiet
Sometimes they might not feel it's always necessary nor feel it's the right thing for them to do. Sometmies they might have been treated poorly in childhood and learnt that staying quiet is in their best interrest.