Music has substantial evolutionary survival value. There’s a theory, which I find totally convincing, that music is the evolutionary precursor to language, the bridge between the cries and gestures of other primates and our own more abstract communication. Read about it here:
Humans’ success as a species is due entirely to our social organization, and music is a crucial tool for group building and bonding, more than we give it credit for in the western world. We think of music as a form of entertainment, mostly divorced from its most basic purposes. But taking the macro-scale historical view, music isn’t recordings of specialists making pleasant background noise. It’s all the emotional-laden patterned vocalization, percussion and gestures we perform, consciously and not. For example, all parents use music to comfort babies. Sometimes it’s in the form of overt singing and dancing with them, but even routine speaking to very young children is mostly musical in content. There’s the singsong cadence, the repetition, and the warmly modulated tone. This “motherese” is universal among human cultures and is probably very ancient.
Music is also a crucial tool for social bonding among adults, for making a tribe feel like a tribe. There are ecstatic chants and dances for spiritual purposes, or for just relaxing and relieving stress. There are work songs to make tedious tasks more bearable. There are marches and fight songs to prepare for battle, and there are lullabyes to lull each other to sleep. We use music to modulate our own emotions and those of others. We use it for courtship. In preliterate societies, music was a crucial mnemonic device, and it’s still extremely useful for that purpose. And modern language continues to have substantial amounts of musical content. Some languages literally use pitch to convey grammatical meaning. Every language uses pitch, rhythm and timbre to give emotional and social coloring to the bare facts conveyed by the words.
We enjoy music for the same reason we enjoy eating, sex and running and jumping. To treat music as a frivolity is like treating exercise that way; it leads to unhealthy and unhappy humans.