Anthropic's primary Capex partner is AMZN. AMZN is presently willing to drop 200 billion a year into Capex for compute to rent to anthropic and others. This 30 billion only needs to fund their rental rates - unlike openai and google who need to put in the upfront capex for their compute as MSFT stopped footing the bills.

An interesting question is whether anthropic's capex needs may grow to the point that they can take down AMZN with them should they fail.