Some of the variance is based on how much people spend on airports and save in the Centurion lounge. Others value it as an ideal, a real escape from the terminal and good food and drink and what that might retail for.
The problem is that, as I wrote five and a half years ago, Centurion lounges have gotten so busy nobody goes there anymore. The experience rarely measures up to the ideal where you experience peace, a nice meal, and even a spa treatment.