Do the others matter?

Yesterday I was going up to the sleeping-quarters in the hospital, I was waiting for the elevator. It arrived but the doors didn't open. I heard people were locked inside but the door just wouldn't open. Two older ladies were coming down from upstairs. Somehow the doors were finally pried open so they could get out. I wouldn't have wanted to stuck inside too, so I asked them: "the doors didn't open, was there some problem?". They didn't even look at me, they just left me there, while one of them answered with complete uninterest in her voice: "well it opened for us, nothing else matters!" (You should have seen her expression, she really meant what she said, it was just astonishing...)
That triggered a thought chain in my mind... so if I get this right "nothing else matters", so if she could get out, the others don't matter at all, she could have also said: "I'm alive, nobody else matters!?" Okay, I know that's a bit extreme, but this casual remark just hit me so hard... especially now as we are waiting for a bone-marrow donor and I've read that in our country there's only a quarter as much blood-donors than needed. So "I got blood and nobody else matters?" I think that's why there's only a quarter of people available as potential bone-marrow donors. I as a living being have all the opportunity to save someone's life sometime just by being a donor. Every human being therefore has a great power inside just by being alive.
(...)
I would like to thank everyone very much, who told me that they would like to test themselves if they're suitable donors.
I took Zorka's blood and mine to the National Blood Supply Service on Monday, 18 July, typing is in progress. When we got the results of this, then we shall know exactly what conditions there are for someone to be a donor.
For starters, usually the brothers or sisters are suitable, however as Zorka doesn't have a brother or sister, we are in a worse position, but it's not impossible. Often there's a high level of tissue-identity even between two complete strangers. So I'm sure "our donor" is somewhere out there, we just have to find him or her.