Is there any convincing data on this point? I know that it was an economist that uttered this theory, so I'll assume good faith when it comes to research effort

Is there any convincing data on this point? I know that it was an economist that uttered this theory, so I'll assume good faith when it comes to research effort or at least diligent argumentation on the behalf of this statement. But without anything to back it up, it just comes off as something it's proponents take for granted as a truism. "Consumerism" (which goes beyond "stuff" and materialism, at least here) has been criticized by many in the western world. Even just leaving aside the argument that involves a finite planet sustaining ever-more needs and desires, I'm not convinced that the average human's needs and desires are infinite in any practical sense. It might be that "more is more", but I also suspect a sharp decline due to diminishing returns as one gets ever more needs fulfilled. How much better does spending 1,000 million on yourself feel than spending 100 million on yourself? Significantly better? I guess we could theoretically get to the point where everyone takes what is in today's currency billion-dollars worth of vacations by going on trips 'round the Solar System. But at some point, maybe before we're at the point of the Solar System joyrides, it just might not seem so exciting any more (travelling to the red wasteland of Mars might not be so exotic and exciting as it is today when a lot of people can and have already done it).