Most Helpful Guy
Photographers are indeed useful, and art itself is transitioning to a digital canvas that better recognizes your Photoshop/Illustrator skills than fine motor skills and coordination on paper.
I was invited to an animation studio (after making impressive character sketches for a pilot) to observe how cartoons are made, and I didn't see people hard at work with pencil sharpners at their side. They used digital screens with styluses.
Sure, pencil and paper have their place, but when it comes to having a career, you need to get industry-grade skills. Painting on a canvas might be dying, but creativity is not dead and never will die.
Most Helpful Girl
This is sloppy and not super cohesive or organized but:
They contribute to new ideas, social movements, promote ideas, and give us some truly beautiful things. Would would each society's culture look like without art? It would be depressing and very monotone worldwide. Each culture and region of the world has developed architecture unique to that region which has ties with engineering and religion. Churches and the art in Churches were designed to inspire awe from its' patrons, the tall Gothic architecture symbolizing connections with the heavens and meant to impress and inspire. Hindu artwork, Buddhist temples and statues. Culture, art, engineering, religion, identity.
Photography captures moments in history. History has many perspectives and is often told by the "winners". They may remind us of human suffering and history we must keep from repeating. War creates an "others" effect where we lose sight in the other's humanity and war photography or just photography of any kind may provide that.
Music and political and social issues: Lennon and Bruce Springsteen protesting the Vietnam war. Can provide a platform for ideas no matter what they are. Can also be exciting, moving, beautiful, pumps you up (to work out to) whatever.
Poetry and stories interact with each individual language. Legends, heroes, and art a source of national pride and create a cohesive identity possibly bringing together multiple ethnicities in a single state. Music - national anthems and national pride.
Art, while having ties to specific countries can also transcend borders and be appreciated by anyone in the world and bring together new communities.
What does art do? It creates and nourishes culture, creates unique diversity, and inspires the world.
I would also say they are not selfish, they have a right to seek their own ends. I also disagree that it is a waste and that it contributes nothing to the world. What a depressing and narrow world view.