The $2T comes from the implied odds (perhaps 10 or 20%) that we get near term AGI or RSI and AI becomes the entire economy, crossed with the odds that Anthropic gets there first and is the runaway winner (maybe 25%).
The trouble, in my view, is that today's revenue numbers are essentially irrelevant to the outcome that drives ~all of the expected value. The market has been pretending otherwise, but fundamentally we're looking at a globally top-10 public company that boils down to a binary call option, and the probability underlying that option is inscrutable. That's never happened before, and an inability to divine a fair valuation properly demands extreme volatility, especially in reaction to capabilities progress.
Finally (total speculation): I think Anthropic knows this. I think they're sitting on something with Fable 5.5 and the surprise outperformance of Opus 5.5 is a tell. They intend to release it just before the IPO and make some big claims underwritten by its performance.