system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is it that rich people's "net worth" is public, but average people's information is private?
gpt
The "public" numbers are estimates, not firm numbers. In the case of public companies' founders, CEO's, etc. there are public disclosures of share ownership and that typically accounts for the vast majority of their net worth so it's used as proxy. There are also public disclosures like stock sales, there might be records of other investments they've made, etc. and the pieces are cobbled together to get an estimate.

For example, if billionaire X owns 50 million shares in the company he founded and it's trading at $100 then we know they are worth at least $5 billion. Maybe they've sold off 10 million shares over the years for living expenses and diversification clearing $600 million, and they've also bought 2 houses worth $20 million, a plane worth $50 million, invested $100 million in other companies and those holdings are now worth $400 million, etc. So they're worth an estimated $6 billion. Maybe it's off -- maybe they blew hundreds of millions gambling, or maybe they invested in Apple options and made a couple extra billion. So it's just an estimate.