It's often used in the context of "à quoi bon", which means "what's the point?" or "what good would it do?" This phrase expresses a feeling of futility or lack of purpose.
Here are some examples:
* "À quoi bon se fâcher?" (What's the point of getting angry?)
* "À quoi bon travailler si on n'est jamais payé?" (What good is it to work if we never get paid?)
* "À quoi bon discuter avec lui? Il ne changera jamais d'avis." (What's the point of arguing with him? He'll never change his mind.)
So, while "quoi bon" can exist on its own, it's more common and natural to use it as part of the phrase "à quoi bon".