Former Enron bosses Kenneth Lay and Jeffrey Skilling stole from investors both to line their pockets and stroke their egos, their trial has heard.
Enron founder Ken Lay is hoping there are brighter times ahead
The comments came from prosecutors presenting their closing arguments at the court in Houston, Texas.
Prosecuting lawyer Kathy Ruemmler said the case centred around "the lies these men told and the choices they made".
Mr Lay and Mr Skilling are accused of trying to hide $32bn (£18bn) of debts at the firm. They deny any wrongdoing.
The one-time US energy giant collapsed in 2001 when the debts were revealed. Thousands of people lost their jobs and investments.
1985: Enron formed
Oct 2001: Enron reports $638m third quarter loss and $1.2bn fall in shareholder equity
Oct 2001: Securities and Exchange Commission begins inquiry into firm
Nov 2001: Enron shares sink to 10-year lows as buyout deal falls through and further losses are revealed at the firm
Dec 2001: Enron files for Chapter 11 bankruptcy
2002: Criminal investigation launched
2004: Skilling and Lay charged over Enron collapse. Former finance chief Andrew Fastow pleads guilty to criminal charges and agrees a 10-year jail term
Jan 2006: Enron trial begins
Mr Lay and Mr Skilling both say that other staff were to blame and that they were kept in the dark.
Ms Ruemmler told the court on Monday that for both men "Enron was their ego".
"Make no mistake," she said. "There is absolutely nothing wrong with getting rich but you can't get rich by deception, by cheating."
The defence will make its closing arguments on Tuesday, and the jury is expected to begin its deliberations on Wednesday.
Mr Skilling, 52, Enron's one-time chief executive, faces 28 counts of fraud and conspiracy.
Mr Lay, 64, the firm's founder and former chairman, is charged with six such offences.
Both could be sentenced to more than 30 years in jail if convicted.
They suffered a blow last week when the judge ruled that jurors could find the men guilty of deliberately avoiding knowledge of massive fraud.
Known as the "ostrich instruction", because it refers to a person sticking their head in the sand, the ruling means prosecutors can present a lower burden of proof to be successful.