Outliving the Social Security Trust Fund
Unfortunately, Social Security funds are not infinite. More than that, according to the 2019 Trustees Report, by 2035, the Old-Age and Survivors Insurance Trust Fund, which covers Social Security retirement benefits, as well as the Disability Insurance Trust Fund will run out of money.
The reason is that the working-age population cannot keep up and cover for the growing benefits of future retirees, such as the largest generation in U.S. history, namely the baby boomers. Starting in 2035, only 75% of the social security benefits will be covered by employed workers, and only up to 2039.