Why do British people pretend to know alot?

I am a university student currently pursing a degree aerospace engineering. Apparently I am an international student and I am concerned with the conduct of the British students. They cl themselves to be the fountain of knowledge and so they are reluctant to attend discussions or even to share what they know. Most of them act like the so called 'lone buffalos'. Consequently, their results reflect their attitude because in real sense most of them are struggling because they think they are a monopoly of knowlege. Help me understand this please!! Does having a discussion undermine your self esteem??