I absolutely think art is a luxury. Just like good food, traveling, going to the movies, and reading good books are luxuries. Humans just need stories, and colors, and new experiences, in my opinion. We can't help ourselves. I don't think there's a single culture on Earth that only eats food to survive and doesn't try to make it taste good, too. Or makes objects without in some way decorating them or making them interesting to look at in some way when possible. To me, luxury is what you make of it and it doesn't necessarily mean expensive.