SSI stands for Supplemental Security Income and is welfare because it’s paid from Federal tax dollars and is “needs based”, ie. income driven. The only thing you’re accurate about is that it’s administered by the Social Security Administration. People receive it if they claim and apply for Social Security Disability but haven’t worked enough to qualify for disability. The threshold for proving your disability is less than actual SSD from what I understand.
It is you who know nothing about SSI. Supplemental Security Income is NOT a Social Security funded program. They administer it but funds are taken from the government general fund. It is for those who haven’t worked and don’t qualify for Social Security. You are taking about SSDI Social Security Disability Income which IS a Social Security funded program under which have to qualify by working enough quarters. Go look it up. I did years ago on the SSA website.