Toxicity
A repulsive cesspool of avarice; that's what the Earth is. Even as we choke to death on our own desires, we scream for more. We demand more. Who is God to defy the foolish humans of their wants? We buy, take, and steal all that's within our reach. Everyone knows that greed will be our downfall, but no one truly cares. When someone is asked whether they would save their child or their fortune, you know they're lying when they automatically give the 'proper' response. I myself would throw away countless human lives in exchange for material possessions. When someone says that they'd kill for something, how many aren't exaggerating? Habitats are destroyed in the name of riches, yet we wonder why the planet is dying, along with all the animals that inhabit it. A soul is toxic, and no animal should ever be cursed with one. They're easy to corrupt yet impossible to fix.