Managers are underlings in that sense too. They don't own enough stock or have enough influence that they would rationally be thinking of the gains they'd make

Managers are underlings in that sense too. They don't own enough stock or have enough influence that they would rationally be thinking of the gains they'd make in their stock. Managers take ownership because they're looking for their project to succeed, they want to advance their career, etc. and the same applies to "underlings"