When President Roosevelt first enacted social security in 1935, the intention was to serve as a safety net for older adults. However, at that time, life expectancy was roughly 60 years. Therefore, the expectation was that participants would not be drawing on social security for very long on an actuarial basis. Furthermore, according to the Social Security Administration, roughly 42 workers contributed to the funding pool for each welfare recipient in 1940.
Of course, given that politicians like to use government coffers to buy votes, additional amendments were added to Social Security to expand participation in the program. This included adding domestic labor in 1950 and widows and orphans in 1956. They lowered the retirement age to 62 in 1961 and increased benefits in 1972. Then politicians added more beneficiaries, from disabled people to immigrants, farmers, railroad workers, firefighters, ministers, federal, state, and local government employees, etc.