As Anthropic is expected to launch what could be its largest-ever IPO, its U.S. clients are shifting to lower-cost alternatives, abandoning its highest-performing AI tools. Data from payment service provider Ramp shows that over two months after the release of Anthropic's most expensive model, Fable5, it accounted for just 11% of consumption, well below prior expectations. This trend has shaken the AI lab's business logic of 'driving revenue through the strongest models.' Despite Anthropic's annualized revenue surpassing $65 billion, its business model faces challenges due to high model invocation costs (more than 2.5 times those of OpenAI's flagship products) and competitive pressure from Chinese open-source models. Corporate clients are becoming increasingly sensitive to AI spending and are turning to more cost-effective alternatives. Despite multiple pressures, Anthropic's overall growth momentum remains strong, but the sustainability of its high-cost business model has yet to be tested by the market.