The gods demand more growth.
If we do not show the gods growth, the game they have created is over. The sun shall not rise again.
Everything is predicated on growth. Revenue must grow. Profit must grow. Population must grow. Crop yield must increase. Jobs must grow. Absolutely everything must grow, even if it does not make sense, for, the gods pull the gold of today from the blood of tomorrows. Grow. Expand. Consume.
We first allay the demands of the gods by being smart. We farm animals. Pool the blood. Streamline processes. Automate them. It is at first a good relationship, for the fruits of the technologies ultimately benefit both us, and the gods.
But the gods often demand more, and our bursts of inspiration and cleverness do not always come regularly enough to keep up with the demands of gods. So we make war with those that have failed to adapt to the new technologies, eliminate those who object, enslave them, and extract tribute. It's not ideal, but so goes the price of keeping the sun.
But eventually, there are neither, nor are there other neighboring tribes to extract tribute from. Yet, we still must grow (for the gods demand it). And with nowhere else to expand to, and no means to increase our own bounties through technology in the short term, we must do something else. And so, with no other option available we begin to sacrifice our own to keep even just the illusion of growth up.
Every day we put more blood upon the altar of sacrifice, to show our power and our growth to the gods. And while we sacrifice to the gods of growth, and keep our bounty, the earth itself becomes consumed more and more by our greed and iniquity. As the blood pools the oceans drain. The skulls of the dead litter the fields. The rains stop. Fires spread.
Where did the rain go? we ask ourselves. Why will the crops no longer grow, why can't we catch any more fish? But in our hearts, we know: we threw it all away to please the gods, and we can please the gods no further. The sun will never rise again. As the village dies and the scattered rival clans - fresh with the memories of all we took from them - come for their revenge as we lay in weakness and famine we will be rendered helpless.