Regarding human sacrifice, whether ancient Mayans or modern Gaians, it’s a simple motivation: more room for the rest of us. It’s a natural mindset for a hunter-gatherer people, for those who don’t understand production and only know about harvesting. If you understand productivity, then you know that people are the greatest asset because they are the source of that productivity. Kill them and there’s actually less for you. But if your brain simply lacks the circuits to comprehend productivity (and truly I think most Leftists lack this capacity to a significant degree), then other people are just mouths to feed – the universe gives the same bounty regardless, so killing them means more left for you to take.