I have no doubt your friend SSI disability claim was denied...up to 60% are on the first attempt....but...it's not based on family income.....it's based soley on the disableds earnings & contributions to SSI....
4. I am disabled, but I have plenty of money in the bank. Do I have to wait until this money is gone before I apply for Social Security disability benefits?

No. If you have worked in recent years or if you are applying for Disabled Widow's or Widower's benefits or Disabled Adult Child benefits, it does not matter how much money you have in the bank. There is no reason to wait to file the claim.
This and more info can be found at
http://www.nosscr.org/faqind.html
My husband makes a very good living as management for the US postal svc...and I was in the process of applying for SSI....his income did not enter into to it...there are many other reasons a claim for SSI disabiliyt payments is refused at the first level...I urge you to get more information for SSI