Fable is strongly believed to be around 10T. The most conservative estimate I've seen is 8T.

Eg: https://www.reuters.com/technology/bytedance-targets-mega-ai...

That reports Mythos as 8T and Fable as 5T, but I think they mean Opus as 5T, which is widely known, eg: https://eu.36kr.com/en/p/3760679047267075?ref=explainx

Both Grok and Bytedance are training 10T models.

> The cost to train and infer that would be insane, even by today's standards.

This assumption is likely what has led to the erroneous failure.

Enterprise compute per rack has scaled multiple fold in the last 3-5 years. Alongside the training efficiency gains & datacenter scale increases, even 50T+ is well within reach at the top end.

Kimi K3 is a 2.8T model that's available at about 1/4-1/3 the cost of Fable from multiple providers on openrouter. The math doesn't seem wildly off.