In my opinion when the Enron decided to develop a system for the company, becoming the first energy company in the industry to adopt a mark to market accounting system, which was a system that allowed the company to attempt to predict (estimate) present income using future cash flows was when the unethical events/actions began to spiral out of control. The amounts (future cash flows) were more difficult to predict than the company planned for, but Enron continued to recognize future profits despite the losses that were actually being produced from the long-term contracts.
Another ethical consideration was how Skilling encouraged employees to invest and buy stock in Enron when they knew the truth about the lack of value in the stock. Upper management (mainly Fastow) created a complex business model almost impossible to understand by any outsiders, and had financial statements that were so confusing to analysts, no one was able to foresee how financially corrupt Enron actually was.
The management system created a dysfunctional corporate culture whose employees only cared about getting a good rating review and bonuses for themselves. The floor traders were even talking to each other and getting excited about the fires and power outages happening in California, which were actually caused by the employees giving the unfair trade advantages. I feel like the Enron