This was the theory that people are subject to natural selection and wealth was a sign of superiority.

Answer: Social class essentialism.

The theory of social class essentialism is one that states that people who are able to accomulate more wealth do so because of their natural advantages. Social class essentialism is a revision of social darwinism. It bases its logic on Darwin's idea of natural selection. It states that people are naturally different in their abilities due to genetics, and economic and social success can be attributed to these.

The risk in endorsing this theory is being unable to notice other social factors that affect achievement, such as gender or racial discrimination.