Social security benefits are extremely non-linear using from 90% down to 15% of income in each range. It also only considers a limited set of your highest years earnings, which can mess with early estimates.

The minimum benefit for someone who worked 30 years making minimum wage is $872.50 per month, 10.5k/year The maximum benefit is $2,861 per month or 35k/year, for someone who made 140+k for 35 years.