Jessica, imagine you were diagnosed with leukemia and told that a bone marrow transplant could save your life -- without one, you had little hope of living very long. Unfortunately, like 70% of people in your situation, no one in your family is a match. And your insurance, like many, won't cover this special procedure.
But! Then you find Matilda, who is a perfect match! What a relief! And Matilda says, "you can have my bone marrow, if you'll pay me $10,000 to transport it to you." But you don't have $10,000. Too bad. Eight months later, you die.
Matilda lives another 60 years. The knowledge is rarely far from her consciousness that she could have easily saved your life, but didn't. Then she dies, too.