Why is life programmed to survive?

[Whateverist]

What about the cells that make up the protective dead layer of our skin?

And even more interesting...what about the 20% of cells that self sacrifice in slime mold stalks so that the others can launch out of the spore head?

That is a good question, isn't it. And yet the 'sacrifice' those 20% make is really no greater than the sacrifice the cells of a multi-cellular creature make in becoming one of a kazillion bone cells or a white blood cell or any of the others including those dead skin cells on the surface of our skin which you mention. Apparently, it doesn't work to anthropomorphize by imputing our subjective states into the actions of a single cell. Very likely neither a bone cell nor any of the mold stalk cells feels heroic. They lack anything we'd recognize as subjective states. But the process of selection works as well with built in 'sacrifice' of individuals for the survival of the kind (species/family/etc) as it does for the selection of individual multi-cell creatures. The living material survives to perpetuate its kind and that keeps the ball rolling, no celebratory subjective states necessary.