If you are highly compensated and in a stable FANNG position, startups might not be attractive due to instability. There can also be some bias. For an example, people who want to work for startups would probably be working at one already, or be an entrepreneur. Obviously there can be exceptions.
The biggest factor will be if the person believes in the startup's idea/product. This can be them wanting a smaller company where they have more control, wanting to help a cause, wanting to work that concept/product, or wanting equity in the company that could be worth a lot.
Without those sorts of motivations, it can be hard for some startups to compete with FANNG on pay, benefits, and stability.
What I'm most curious about is the Hiring Manager's POV. Do they, in fact, even want FAANG engineers?
Money aside for a moment, do startups require too much of a transition in culture (small, fast & unpredictable) or skills (more generalist & unsiloed) for FAANG engineers to perform successfully?
The most common issue I saw around FAANG engineers and startups was actually retention (which is more broadly an issue throughout engineering). Owning a substantial piece of a company is an exciting thought when you first join, but after a year and a half of making 60% of your old salary, in which the startup has had enough ups and downs to make you question whether this equity will ever actually be worth anything, moving on can be very attractive.
I remember a well publicized story that talked about a startup trying to poach a google engineer (they offered him $1M but he turned it down because Google was paying $3M). So I guess some startups want them depending on the skillset or reputation.
With shorter tenured engineers who’ve never worked outside a larger company, watch out for over-engineering. But those who are comfortable launching non-terascale solutions to non-terascale problems can typically adapt well.
People who have gone back and forth often have a good perspective and are great to work with!