what’s the use (of something)
From Longman Dictionary of Contemporary Englishwhat’s the use (of something)what’s the use (of something)spokenPOINTLESS used to say that something seems to be a waste of time What’s the use of decorating the house if we are going to sell it? → useExamples from the Corpuswhat’s the use (of something)• My granda is dying there and what's the use?• And what's the use of being on observation when you can't observe anything?• You're a bloody animal, Cullam, without an animal's ... Oh! what's the use?