These people are already massively rich and likely have opportunities to join any tech org that's growing, and any of those opportunities could make them even richer. It doesn't really explain why Anthropic is their apparent best option.

It's probably just the most interesting and challenging tech company right now (that's hiring high profile roles?). There's lots of other companies doing interesting things but if your expertise is software applied to a complex domain, Anthropic probably comes out on top.

> These people are already massively rich...

Maybe they want the highest likelihood be even more richer and Anthropic gives them this.

Equity in a $1TN company pre IPO is very attractive than investing in startups and waiting 10 years for an exit.