> (on purpose?)

As Upton Sinclair put it, "It is difficult to get a man to understand something, when his salary depends on his not understanding it."

That quote is just the tip of the iceberg of Sinclair's work, though. He wrote about how when a person's livelihood, reputation, or financial well-being relies on a specific status quo, they often find it impossible to see the logic or ethics in changing it. It can be very difficult for them to confront such issues objectively.

He also wrote about the question of cynics vs. true believers in this situation. For the true believers, he pointed out that the only way for them to resolve their cognitive dissonance (while maintaining their lifestyle) is to block out the truth entirely. They stop trying to understand because actually understanding would be too painful.