Making of the FAT man

Once upon a time, there was a cool boy. Cool means just being normal and not being a weirdo. He was like any other boy of his age. He had couple of very close friends. He was in the local gunda gang of stamp collectors, bullying and blackmailing decent kids to get hold of the rare stamps from their album or striking uneven deals like exchanging just 3 American stamps for their rare stamps from Dominican republic. At the school, he liked the eagle. He spent time, betting to his friends that Eagle will turn back and look at him, whenever he gets up from his desk, or Eagle will give the EXACT same answer that he gives for the teacher's question: "What is your future aim/goal?". He sucked in all the subjects in the school except at Maths. He never cared for studies. Life was simple for him then. Playing street cricket. Chatting for hours with his friends at the junction where he and his friends part on their way back to home from school. Fighting vehemently for his right as the first born to be the one who eats the first dosa by his mother during dinner. shouting at his brother/sister because they won a game of 'rummy'.

Then something happened. He doesn't know what it is. His marks in the school started improving steadily. As months progressed, his weight increased proportionally to his marks at different courses. He did very well in the board exams. He moved away slowly from his friends circle. Started closing up. His only aim was marks, marks and marks. He didn't care about anything else. He finally ended up with an Engineering degree and a job and loads of FAT in his body. By now he is old enough and has the ability to think about the complexities of life like love, friendship, meaning of life, job satisfaction etc. Even though he has this potential to think about higher things, he still is just content with mundane things like marks/grades and feels EXTREMELY HAPPY for making an A in the course that he did this summer, as a part of his PHD program. What is that something that made him so hungry for marks and grades?