Why do you make music? Answering this question may seem trivial, but it may also help you refine your creative process. Just like a better understanding of audio engineering will help you create better mixes, a better understanding of the reasons why you're making music in the first place will help you become a better musician.
Reason #1: I enjoy the process
Not only this is a valid reason, but it's often necessary to enjoy the creative process in order to achieve other goals. Let's say you want to be famous, if you don't enjoy the creative process, you'll just feel stressed.
It's the same thing if you want to make it a career. If the creative process feels like a burden, you may need to consider another career path or re-invent your creative process.
To make the creative process enjoyable, ask yourself what made you enjoy it in the first place? For me, it has always been about discovery and happy accidents. So my creative process is driven by curiosity.
Reason #2: I want to express myself
Sometimes, the only way to express something is through music. It could be for legal reasons: you've been abused but can't go to court because of a lack of evidence. In this case, expressing your pain through music can be the only way to cope with your past, and it can also be the only way to survive.
It's also a much more healthy way to deal with this kind of problem than drugs and alcohol. A lot of very dark music has been created to describe the darker side of human nature. And this kind of music reminds those who create it that they are not alone.
Reason #3: Collective joy
For other musicians, the situation is completely different. They love life, they've been lucky so far and they want to express their joy to the world. Or they chose to focus on the good side of things. Light-hearted and fun party music is created for this very reason.
You might find the creative process hard, but you're motivated by the final product and the experience it will create at parties all around the world.
Your music is the sonic equivalent of a dessert. And it's a perfectly legitimate reason to make music.
Reason #4: Social approbation
When I was studying marketing a couple of years ago, there was this idea about finding the deep reasons why people buy something. An example of an ad from the 1920s that advertised a book to learn how to play the piano was always shown to illustrate the concept.
In the first version of the ad, you could see a picture of the book and the title said: "Learn to play the piano today in 5 easy steps!". The ad wasn't performing very well.
In the second version of the ad, you could see a guy playing the piano joyfully with his family and the title said: "Impress your friends and family with your piano skills!". Suddenly, the ad performed very well and the books were selling like hot cake!
The bottom line
While all the reasons are valid and legitimate, I think that enjoying the process is what matters most. Doing something you hate for social approbation would be sad. Trying to express yourself through means you don't like won't last very long.