The light of the righteous rejoices, but the lamp of the wicked goes out.
Why? Why does Solomon need to keep reminding the people of their need to think of righteousness as something they want? Something good for them? Why does he keep making connections and illustrations? He ties righteousness to things like light, wealth, house, family, food.
The reason is that we forget. Our world, our selves, the devil combat continuously the idea of righteousness, tying it instead to poor images, such as sad, lonely, crazed, starving, violent people. And so what is obvious to us needs relearning every day. For we are weak, and subject to slipping.