Which groups of people did not benefit from the prosperity of the roaring twenties?

Black people and farmers. Yup the guy has the right answer

Black people were particularly badly hit by the problems in the country as they had always done the least skilled jobs. Almost 1 million black farm workers lost their jobs, many moved to the cities where they shared similar experiences with the immigrants; low paid jobs and poor housing conditions.

Farmers also had a hard time in the 1920s and almost half the American people were engaged in agriculture. The reasons the farmers were struggling were that after the war, Europe imported far less food from the USA.