How did Gatsby or Tom illustrate the corruption of the American dream?

The American Dream is that anyone, no matter how humble one's birth, can become whatever he wants in life as long as one is willing to work hard to achieve that goal.  Jay Gatsby, born James Gatz, knew from an early age that he did not want to live a life like his parents who were poor farmers from North Dakota.  In the book his father, Henry Gatz, brings to Jay's funeral, Mr. Gatz points out to Nick, how as young as age 12, "Jimmy" wanted to make something of himself and had firm goals and resolves.  At age 17, James Gatz remade himself when opportunity presented itself in the form of Dan Cody into Jay Gatsby.  He traveled with Cody and though he never received the money Cody willed to him, he received an education and had the flames of his American Dream fanned by what he learned from Cody.  Jay Gatsby's American Dream was to become rich and live the good life.  He had his goal firmly in his mind when he was a young lieutenant at an Army camp and met Daisy.  He never intended to fall in love with her, but he kissed her and he did fall in love with her.  After that, his goal became Daisy.  When he had to leave for war, Daisy didn't want to wait for him and besides, he was not wealthy and she was.  Daisy married Tom, a man as rich as she was because that's what rich people did - they married rich people.  Losing Daisy to Tom corrupted Jay's dream and it becamea two-part dream: get as rich as possible as quickly as possible and get the Daisy of that courting period in Louisville before Jay was sent overseas and before Daisy married Tom.  Essentially, Jay wanted to turn the clock back five years to those days in Louisville.  He wanted the Daisy of five years ago before Tom and before her daughter Pammy.  That's impossible - as Nick told Jay, "You can't repeat the past." All of Jay's efforts were put into amassing a fortune, which he did largely through illegal means because he was in a hurry, and into gaining back that Daisy.  He wanted her to say that the last five years had never happened; that she had never loved Tom.  She couldn't do that because she had loved her husband at one time - as much as Daisy could love anyone but herself - and she certainly could not "undo" her daughter's birth.  Had Jay's dream not become corrupted by wanting what he could not have, he would have lived.  There would not have been an accident because there would not have been the dramatic confrontation in New York City that caused Daisy to jump in the car and leave.  Jay's father told Nick that if his son had lived, he might have become someone great.  He was right; Jay had the drive and the dream.