Yes, their employees are making lot of money but where her money ends up going? A large part of that ends up paying rent in a region where there are many others making similar wages like you, and trying to outcompete you out of the best property you can choose to live.
Mostly people at headquarters or major offices get paid large salaries.
Executives make decisions where to open office, they've upphand on the info and have access to money, they buy the land in and around the region where office will be setup, where their employees will want to live.
That way half the money they pay ends right back into pocket of executives while FANG employees have statisfaction of making highest engineering wages.
It doesn't matter how much you make, if you still find yourself doing the same thing you were doing 5 years ago, perhaps, all that money didn't bring you much.
Now, there are exceptions to this where people saved up their salary and launched another business into huge success, yea those benefit the most. But most of the FANG employees will find themselves doing similar job after 5 years, so...
How exactly that extra money has changed your life? Are you driving Buggati or Bentley to your office? Do you have celebrities (male/female -depending on your orientation) caressing your hair while you hack on the code? Did you start a school to teach underprivileged kids?
As we can see most of these luxuries are still not available to majority FAANG employees regardless of how much they make. It's the money on paper, it doesn't buy much power. To have real power in society, having more money than your peers is not necessary - what you need is vastly more money and influence over other people.