The SSD income amount is determined based on the earnings record of the person who applies for payments. The amount is based on lifetime earnings at jobs where the worker had taxes withheld for SSD insurance payments. The severity of the disability and personal assets are not factors.
A complex formula determines your actual payment amount using your income record from before the disability. Your average indexed monthly earnings (AIME) are put into a multiplier – 90% of the first $1,204, 32% of AIME from $1,204-$6,172, and 15% of any additional income up to the maximum amount.