I've never worked at a FAANG company but, for when you do reach you do choose to stay are go, can you put a burner email in your profile? A lot of engineers at startups, like myself, want to work with talent that is skilled enough to get into FAANG bit too bored of the extremely glacial pace these companies work at. On a more on topic note: I've heard about, and observed, similar behavior from friends of similar comp…
For example: Optimizing compile time (no need to invest for extra 1 minute speed up), working on high quality labelled data (i came from ML background, this is not possible in most of startups), analytics on data (questionable ethically), working on Ad platforms, working on large scale system.
In the last, Imagine, even making simple changes have bigger impact on real world.