Jobs which require a belief to perform sincerely, select people who hold that belief sincerely.

This principle should undo a lot of cynicism. Yes, eg., people in marketing often "really believe" their efforts are a net-positive, and no it isn't often, "mere cynicism" on their part.

Rather, what has happened, is that most who view marketing cynically, do not take a job in it.

We often misidentify this process of selecting for sincerity as a psychological-reality in those who are selected. Marketers "make money through cynical means" whilst sincerely believing they don't.