That sounds reasonable given that 10% of software developers are talkers that need someone to output something that looks like a deliverable.
We were however talking profits here, not revenue.
That $1bn number was in a paywalled Information article which was then re-reported by TechCrunch so the actual source of the number isn't clear. I'm assuming someone leaked to the Information, they appear to have some very useful sources.
I doubt this is just US developers - they've boasted about how successful they are in Europe recently too:
> Businesses across Europe are trusting Claude with their most important work. As a result, EMEA has become our fastest-growing region, with a run-rate revenue that has grown more than 9x in the past year.
https://www.anthropic.com/news/new-offices-in-paris-and-muni...