I've had plenty of coworkers who've been at Google or Apple for longer than 15 years, but what I've seen is people will usually jump after 4 years for even more comp or go the startup route. So those FAANG salaries are like the lower bound for most. Of course, some people will just save/invest and retire after 6-10 years, that's fine too.

Interesting hypothesis. Where do you think they go?

I’d say it might seem this way because of the hyper growth. Most people at FAANG haven’t been there long, because they haven’t been big that long.