I think lots of those who stay on long-term in that environment, say >3-4 years, effectively become institutionalised, condemned to spend the rest of their life philosophising about whether they can ever be L8 material. These are people who are, by and large, smart but not wise. Yes, the money is good, for an employee, but it barely equals what even a small business owner could make - and these are people whose smarts would allow them to thrive in the software niche, at least with a minimal amount of commercial nous.
The truth is that FAANG (or FAAG, considering what's going on at Netflix?) keeps these people there by creating a value system. If you've ever read the internet-classic 'Five Geek Social Fallacies' post (https://plausiblydeniable.com/five-geek-social-fallacies/), you'll know that people like us - frankly - are suckers for taxonomy. If you tell them that they are the best because they work for you, and the only thing that can make them any better as an engineer is creating maximum returns for the Borg, and surround them with others who mirror and validate that behaviour, they will fall for it for the rest of their lives.
Don't fall for it. There are a fuck ton of smart people at FAANG companies – that's one of the few marketing points which is unvitiated in its merit, they do scoop up very many of the smartest (again, smart-not-wise) people in the world – but that doesn't mean the only way to be smart is to join. It doesn't mean you - as a unique human being - will be happy there. Carve your own path, be suspicious of people selling you axiologies and hierarchies, find a middle road between excessive cynicism and excessive credulity.