Music can do so much more than just paying rent. You can impress your future wife with your playing or singing. It's a form of therapy for many.
It's true it won't pay the bills, but knowing one instrument is a good skill that differentiates you from others.
How are you going to impress your future wife with music skills if you can’t afford an instrument to play?
Or are you suggesting one should also prioritise buying a guitar over paying rent too?