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

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.