Financial games + some acquisitions drove GE's price / earnings ratio to 59 in the year 2000. That screams "this isn't real"! It's like watching a child build an extremely tall block tower and thinking maybe this can keep growing!!
The stock had started to fall by the time he retired in '01. He timed it perfectly. His exit package was probably worth around half a billion dollars. The investors, employees, etc... were the real losers.