"Wealthier socioeconomic groups
recently show more longevity
improvements than poorer
socioeconomic groups."

--	Donald Fuerst Senior pension fellow American Academy of Actuaries Testifying before the U.S. Congress 2013-June-02

 
In other words, the life expectancy for
higher-paid people is increasing faster
than it is for the average person.  Thus,
higher-paid people will receive Social
Security benefits longer than the average
person.