"Huffing their own farts" comes to mind. Instead of building Artificial Intelligence, they were building Artificial Human Centipede.

I'd never considered that the 'Gray Goo' scenario[1] or the Paperclip Maximizer, might be informational and digital rather than physical. LLMs might turn every bit of computer storage into slop (goo) and then cause us to go mad turning the Earth's resources into making more computers (AI datacenters) to hold more goo. The GrAI Goo catastrophy.

[1] https://en.wikipedia.org/wiki/Gray_goo

Let's hope just mind, not brains.