Lots of people working for AI labs have other AI labs they could work for, so their decisions will be made based on differences of remuneration, expected work/role, location, and employer culture/mission.

The claim above is that OpenAI loses to other labs on most of the metrics (obviously depends on the person) and so many researchers have gone there based on higher compensation.

Not what the phrase means, when you decide to take a vastly less lucrative offer you’re working for something other than money.

How many people do that out of the working population?

Millions take a noticeable pay cut, it suppress wages in many fields.

It’s one of the reasons so many CEO’s hype up their impact. SpaceX would’ve needed far higher compensation if engineers weren’t enthusiastic about space etc.

Probably most people working for non-profits or any level of government.

Arguably anyone who's working in a something they're "passionate" about.

Well - only if they had alternatives.

Obviously this is not the case, and you're deliberately choosing to misunderstand the point.