The most important question is whether they make or lose money on each customer, independent of their fixed R&D costs.

If they make money on each customer they have a credible business - they could become profitable even with their existing R&D losses provided they can sign up enough new paying customers.

If they lose money on every customer - such that signing a $1m new enterprise account costs them $1.1m in server costs - then their entire "business" is a sham.

I currently believe that Anthropic make money on almost every customer, such that their business is legit.

I guess we'll have to wait for the IPO paperwork to find out if I'm right about that.