The notion that people live much longer now than back in the 1930's is sorta incorrect. Life expectancy at birth in 1930 was indeed only 58 for men and 62 for women, and the retirement age was 65. But life expectancy at birth in the early decades of the 20th century was low due mainly to high infant mortality.
A more appropriate metric for this discussion is probably life expectancy after attainment of adulthood. The average life expectancy at age 65 has increased an average of 5 years since 1940. So, for example, men attaining 65 in 1990 can expect to live for 15.3 years compared to 12.7 years for men attaining 65 back in 1940.
Average Remaining Life Expectancy for Those Surviving to Age 65
(M) (F)
1940 12.7 14.7
1950 13.1 16.2
1960 13.2 17.4
1970 13.8 18.6
1980 14.6 19.1
1990 15.3 19.6
https://www.ssa.gov/history/lifeexpect.html
Not only that, but life expectancy gains have been concentrated among the affluent, you know, the people who need social security the least. When you raise the retirement age you're basically screwing poor people so that you can keep paying benefits to rich people.
