Being shy is not a good thing as this do not helps in showcasing your capabilities. One is not able to work according to his/her hobbies. This is all because of the thinking of the person that he'll be humiliated if he did something wrong. He don't feel comfortable to do so. But being shy can harm not only your present but also your future. At present it can harm you in your grades specially in co-curricular activities as that is the only platform to showcase your talent and in future it can harm you regarding your jobs as at that time you might not feel comfortable with your colleagues. So make your friend understood with all these facts.