This could be for a number of reasons. First, they might want to study more and require a study environment to motivate them.. Though that is usually not the case because even before they got to their final year session, they are already anticipating when they would graduate. The second reason might be because they dread their going home without a good result to boast of. Also, this is not really a sufficient reason to hide behind.
If you ask me, I will tell you that graduates do not want to leave school because they do not want their allowances to cease just yet until they have enough to go by on their own. They do not even call their parents for their convocation ceremony because that would announce to the world that eventually, they have finished their Never ending quest for qualifications. Well, that would be believed by the unlearned because most people now know that going to the university is no longer enough to secure a job. Although it is necessary for those who would like to work in government offices and not to serve as messengers, to hold on to a reputable job, one needs more than a university degree.
So, what do you think? Why would I finish University education in Nigeria after a 4 (+ X) years and not happy to go home?

Well, I may agree with on some level but really, don't you think at some point, someone needs to grow up and stop playing around. one can't be young forever. Another reason why it should bother me why graduates would rather stay in school to get by while wasting away precious time they could as well spend thinking through what they want from life. It doesn't matter how many years old someone might be, at a particular point in one's life, one would ask themselves why they still got to live the life they are use to, why they couldn't just leave their comfort zone for a change and get a life. Some times, it could be pathetic but, really, can I blame them in our country where no one can boast of social security, economic stability nor political stability. I was just wondering what we can do for graduates in our country to make them glad they went to school. What do you think?