There are many reasons to change job. The pay is always one of them (if you don't work for money, it's not called a job, is it?).
> join Anthropic because of its remarkable commitment to the responsible development of AI for the long-term benefit of humanity.
Obviously, it's better to believe that what Anthropic is doing is good for humanity when you decide to go working for them. But it is at the very least debatable.
Not at the same scale as this, but I've seen friends deliberately choose to get paid less, perhaps much less money, because they wanted to do something. Video games for example, does not pay well, but it may be your passion. Banking pays very well, but it's hard to find any significant emotional involvement.
You can probably argue that's what I did, but it's complicated because I'm hard work. I can't stand debt but I also don't like the feeling of not knowing how to spend all the money. I can say that it's surprisingly hard to get people who are hiring you to accept that (a) the number you put in their mandatory "previous salary" box is correct and yet (b) yes you did understand that they have fixed pay scales and can't possibly match that.