That's not how any of this works.
Anthropic is playing the long game; they're not going make a short-sighted decision just so they announce a profit for one quarter, which doesn’t mean much because it won’t be a sustainable profit since they're going to need to spend a ton of money on training and compute over the next few months.
That's why they did a G funding round for $14 billion in February and $65 billion in May.
I suspect one reason for switching Fable to API usage for the near future is they don't have enough compute for their enterprise customers and every hobbyist on their $20/month Pro plan, 80% of which don’t need Fable 5 anyway but that won't stop them from using it as much as they can.