Pournelle’s Iron Law of Bureaucracy states that people inside any bureaucracy split into two groups: those who care about the group's real mission, and those who care about the survival and power of the organization itself. The second group always wins, takes control, and makes the internal rules. [1, 2]

The Two Groups

The Mission Group: These people try to do the actual work. Teachers who teach kids or nurses who care for sick patients are good examples. [1, 2, 3]
The Self-Serving Group: These people protect the system. Administrators and union bosses who defend bad workers or make more paperwork are good examples. [1, 2]

Why the Second Group Wins

Focus: Self-serving members spend 100% of their time playing office politics and building power.
Distraction: Mission-driven members are busy trying to do their actual jobs.
Rules: Once the self-serving group takes power, they write the rules to hire and promote people just like them. Over time, the original goal of the organization fades away. [1, 2, 3]