Question one: How much did this cost OpenAI?
Question two: Why are OpenAI spending that money taking talent from Google, who can definitely outspend them for talent, and not Anthropic, who are leading the market and are at least somewhat financially constrained.
Reporting on this seems to indicate that people at Anthropic are significantly more loyal, and that attempts to poach by OpenAI and Meta have been largely unsuccessful.
Their options are probably insane sunk cost, hard to steal an engineer who has Xm in potential gains if they choose to stay.
People seem to have turned down offers that would have netted out more upside for them, so it doesn't seem to just be that. Anthropic seems to lure in the true believers, whereas people are highly skeptical of Sam's motivations these days (particularly after how much safety/alignment has been reportedly cut).
But I'm sure for at least some folks, this is true, given recent valuations.
Allegedly OpenAI is struggling to jump to bigger models and had serious issues in the past (4.5) and also allegedly Shazeer is just the right guy for that. OpenAI is having issues hiring talent as most SF-style people want to go to Anthropic. Shazeer seems more politically aligned with OpenAI. But it's all speculation.
Anthropic is a cult making a god.