Your Jane Street numbers are not even close. They're required to report this stuff in the UK, which shows revenues of $229MM (see https://find-and-update.company-information.service.gov.uk/c...). And that's just the UK revenue - most of the business is in the US. I would estimate closer to $1MM/head.

Profit matters, not revenue.

Where do you think most revenue goes? Employees.

Depends on the company. For example most of Walmart's revenue goes to buying goods to sell. Apple sells physical products and hence will spend a lot of money acquiring the physical parts etc, you can't really compare their revenue to for examples Facebooks revenue.