Life isn't precious to Nature, but it is useful. Humans aren't precious, but we can be useful to each other and Nature. What, then, distinguishes humans as particularly good or bad for Nature's future (or our own)?
I submit it is our ability to foresee and act on imagined futures. Nature only offers opportunity to contribute or die off. At one time, humans learned to thrive by combining our Executive Functions, so overcoming our evolutionary fears and reactions, forming intentional, cooperative groups (actual humans, in definition). It worked until we invented religions(marketing), and spent our gains dividing ourselves for profit and power. Civilization(city-based society) separated us from the real environment and allowed us to forget the difference between needs and desires, while favoring bullies, competition and aggression. We have sometimes tried to reform cooperative societies, but the speed and power of aggressive action almost always gets more support, especially when morality/merit is relegated to numbers on a profit sheet.
So, all that said, the answer to your question, "Why is life so mean?" is
"Because we made it that way."
What can we do about it? To start, we can simply do a lot less of everything that costs money. The more money that gets involved, the more detachable meanness gets applied to create, borrow and hoard money. "A corporation is a pile of money to which a group of men swear moral allegiance."- Wendell Berry
The more we do for ourselves and each other without money being involved, the more we engage in our local reality. If we use our creativity to protect and encourage Nature's processes, the less we take away from the resources future people need.
Conversely, the more we follow money's algorithms, the less we can care about our own. In today's world, we have become dependent on these algorithms, and so, in a chicken and omelette situation, we need to start breaking some eggs to be able to keep feeding chickens in the future. Optimists think we can keep feeding more chickens, but the Invisible Hand Job robot chickens of our technotopian future won't want us unless we intentionally make them so.
