what's the use of

What's the use of waiting?

À quoi bon attendre ?

— The Cranes Are Flying (1957)

Then, what's the use of these electric wires?

Alors, à quoi servent ces fils électriques ?

— Swades (2004)

What's the use of it?

À quoi ça sert ?

— The Conformist (1971)

What's the use of movies like this?

À quoi servent des films comme celui-ci ?

— The Asthenic Syndrome (1989)

What's the use of going?

À quoi bon y aller ?

— The Conformist (1971)

But what's the use of that?

Mais à quoi ça sert ?

— Like Stars on Earth (2007)

Sometimes I'd just like to cry, but what's the use of crying alone?

Parfois, j’aimerais simplement pleurer, mais à quoi bon pleurer seul(e) ?

— Office Romance (1977)

Otherwise what's the use of it?

Sinon, à quoi ça sert ?

— 8½ (1963)

What's the use of talking?

À quoi bon parler ?

What's the use of great ideas if we don't actually do something?

À quoi servent les grandes idées si on ne fait rien concrètement ?

— The Wave (2008)