Is it really a secret, when Anthropic posted a project of building a C compiler totally from scratch for $20k equivalent token spend, as an official article on their own blog? $20k is quite insane for such a self-contained project, if that's genuinely the amount that these tools require that's literally the best possible argument for running something open and leveraging competitive 3rd party inference.
If you get paid $120k and could do it in 2 months, seems about right
An article over, these claims are exaggerated - they have dumped the tinycc compiler, not written one from scratch.