We administer retirement, disability, survivor, and family benefits, and enroll individuals in Medicare.
Social Security provides retirement income for almost every American worker.
Ssa.gov
An investment fund is a supply of capital belonging to numerous investors, used to collectively purchase securities, while each investor retains ownership and control of their own shares.
Investopedia.com
The only thing not making it an investment fund is that the government forcefully takes the money and you don’t own the money after it is taken.
The average person gets the majority of their retirement income from SS.
Ask the average person what SS is. They will say that it is a retirement fund. What is a retirement fund? An investment fund.
Social insurance, as conceived by President Roosevelt, would address the permanent problem of economic security for the elderly by creating a work-related, contributory system in which workers would provide for their own future economic security through taxes paid while employed.