I sort of agree, but would say that fairy tale part might be better described as a psychological effect, but still consistent with your questioning it as other than a hard economic fact. What I mean is that the person's psychology may change as they become accustomed to a specific standard of living. For example, if someone grows up driving new BWMs, they might see it as "normal" and not derive as much joy from it as someone who got a new BWM after working for it for years. So it seems that the axiom is specific to an individual and their psyche, which provides provides few beneficial use cases beyond understanding that if people have 'a lot' of money, then money might not be a strong motivator.