The individual value of an IC outside of Meta is most certainly lower than what they get paid there. The company provides so much value that it raises the ICs value inside Meta. It's win-win.
Getting "paid more than you'd be worth anywhere else" has its price.
I worked at a big tech company and saw a good portion of my team buying houses at the same time, a lot of which were a lot more junior than me. I know what they bought, where and roughly how much it cost. A lot of the time, they're only making it work by having (2) two big tech salaries or 1 big tech salary and a second senior-level tech salary. My thought at the time is that it was very high risk.