What is Walter trying to say when he refers to African Americans as "the world's most backward race of people"? Does he seriously believe this?

The question statement is referenced from the article A Raisin in the Sun written by Lorraine Hansberry

In A Raisin in the Sun, there are numerous characters, young and energetic but somehow are frustrated out of their situation and dreams. One of the character is Walter who wants to earn money and become a successful bussiness man.

In the article, when he says the lines given in question, he actually does not mean it, but it shows his feeling about black people that in general they are the ones who dont want to achieve much unlike him