According to Google each day 151,600 people die each day.
Death is a natural conclusion of life.
Your troublesome sibling ought to meditate that soon it will be their turn.
It is foolish to risk your life for nothing -- and you WILL be risking your life -- do you think that everyone survives donor surgery?
You cannot save the world, and you cannot save those too dumb to want saving.
My condolences.