I think it's more like 1 employee makes 10M net revenue, and 9 employees coast on their success.
As an example, a super star programmer, requires support from DevOps, QA, PM, EM, UX, Docs to deliver the great results. Alone not a super star anymore.
To be more precise: figuring out which ones are useless may cost more time/money/effort than you would save by removing them.