The AI bubble music stops when one of these former-darling companies has a complete crashout rather than a "successful exit". The investors keep investing because even largely-failed products get acquihire paydays
Note that Meta paid ~16b for Alexandr Wang, and Google paid ~3b for the windsurf executive team. You are making a category error -- the talent pool isn't "ML researcher" it's "competent leader"
They’re buying the customers and the brand.
What you might pay for is market signal + model distribution. Grok needs a story for why enterprises should switch. "The model that powers the tool you already use every day" is a much easier enterprise sales pitch than "our LLM benchmarks slightly better." The $60B is at least partially buying the answer to the question: why should any company bet on xAI?