There is an enormous difference between paper money and real, liquid money. There is an enormous difference between the headline price an investor invests at, with all their Preferred rights, and what an employee can actually cash out at.

There are very, very few cash exits of $1B+ in any given year. And far less than the majority of those have rights that allow employees, or even founders, to cash out at, for example, the sky high initial IPO market cap pop price.