When there’s a famine in the land, people leave for brighter horizons. They find food; they multiply; they get rich.
It happens to Abram in Egypt, to Jacob in Haran, to Israel in Egypt. Exile agrees with Israel; they always return with children and treasures.
Except Naomi. She goes to Moab during a famine, and her family shrinks as she loses husband and sons. She doesn’t return rich. She is literally emptied. She comes back with nothing.
Nothing - except Ruth. Which is enough. Ruth gives Noami a child and marries the wealthy landowner Boaz. Ruth is the plunder of Moab; she has the potential for fruitfulness.
Naomi sees it. She recognizes that it was better for her to return from exile with Ruth than with a house of children, because Ruth is “better than seven sons” (Ruth 4:15).