Because they have nothing better to do. They don't like attending classes as they are waste of time. They don't like doing assignments because they are waste of time. They have to somehow spend their 4 (or more) years in IIT and get out of here with a "fat" package. So, what better way to "productively" use their time than playing Counter-strike with their "friends."
I like to blog about various topics ranging from education in IITs to social issues in India and US. All opinions and views presented here are my own and not of my employer.