The phrase "haves and have-nots" basically refers to rich people ("haves") and poor people ("have-nots").
In life, there are haves and there are have nots. That's just the way it is.
"Haves and have-nots" sounds even more basic than "rich and poor". Even in a society without any money, there can be "haves" - people who have land, food, etc. - and "have nots".