Quoting Freckles Ford:" Because you don't want someone to die? o_O Clearly... "
Yes, but that's a selfish desire, not an altruistic one.
Another of the arguments against GM is how selfish it is... let's be honest, for every altruistic person out there, there are 100 motivated first and foremost by selfish motivations.
Look at any charity for any disease in existence. 99.9% people involved in the charity became involved when someone they knew, themselves or someone else, got the illness. They obviously don't want anyone else to get it either and want to help everyone who has it, but primarily they want to cure or heal the person they know. The primary motivation is a selfish one, even if much good comes of it. So selfishness isn't always bad, because it can drive us to actions that end up helping others as we help ourselves, too. You don't tend to see people deciding to champion the cause of an illness that has no benefit for them at all, no one they know might end up benefiting from the treatment, etc.