Because of empathy I guess? I can go on living perfectly fine without my savings ("fortune"), without losing any quality of life really. So if I can make the lives of five people's families and loved ones better, why wouldn't I?

Not everyone has much of a fortune. In fact many people have net debt

Cause most likely they will be thankful and reward you financially and in the long term you might get your fortune back and then some. You have to play the long game! xD