It’s not a $$$’s spent thing.
It’s the pursuit of accurately reproducing music with sound equipment.
That accuracy, can be empirically based, or, emotionally based. Meaning, one can try to reproduce the sound of an acoustic guitar as it would sound in your room, or, try to reproduce that sound based on how you feel a guitar should sound, or perhaps how a guitar sounds in some important memory you have of a guitar.
Whatever the case, it’s about achieving a specific quality of music reproduction. If you want your music to sound a certain way, you need equipment for that.
Some listen to equipment, most listen to music. Everyone listening to recorded music, listen through equipment.