David is a janitor because he can't find a higher paying job, even though he has a college degree. He believes that he is to blame for his inability to find a job with higher wages, because everyone in the United States has an equal opportunity for success. David believes in:

Answer: Competitive individualism

Explanation: David believes that his inability is responsible for not finding the right job, and ability and hard work are prerequisites for success, which is in fact competitive individualism. That's why David thinks he can't find a job for which he has a degree because he doesn't have the ability or the trait to do something like that. In other words, achievements as well as downs or failures depend on the merit of the individual, hard work and required traits are prerequisite for success and achievement and, on the contrary, insufficient individual work and traits which are not good enough lead to failure.