The point of that quote attributed to Steinbeck wasn't that it is bad to have personal dreams and goals. Nobody thinks that. Whether you agree with it or not,

The point of that quote attributed to Steinbeck wasn't that it is bad to have personal dreams and goals. Nobody thinks that. Whether you agree with it or not, the quote is saying that poor people aren't recognizing what is in their own interests and aren't sympathizing with poverty because they do not recognize their poverty as something real. It is not making fun of the American Dream to point out that many people in the US are poor and will remain poor despite their hopes, dreams and efforts. Limitations on class mobility are real.