The 20% people remind me of the "sociopaths" in the Gervais principle[1]. They are the people who are just waiting for the right moment to make a play for the top. Doing the rest of the 80% work is not visible or important enough to catapult them to the top. The 80% is left for the "clueless" group who does all the work but never gets recognized or moves up.

[1]:https://www.ribbonfarm.com/2009/10/07/the-gervais-principle-...