I am one of the millions who love to write. Who HAVE to write. Even with my emails and letters, I take special care to use just the right words, to put a positive spin on what I communicate, and do my best to be typo-free.
In writing novels, I especially want to express exactly what my characters are thinking and feeling, but do it in a voice and style that is evocative and memorable.
This has sometimes led to the dreaded "purple prose," so I have to be careful!
As with a lot of writers, I interject into my stories values and activities that I practice in my real life. For example, my heroines have talents, often domestic-based, that are their power in the world. Llyrica in Loveweaver is a weaver, and Amber in The Maiden Seer can read runes. Another character I wrote could sew brilliantly; I, myself, was a dressmaker for many years.
The heroine, Verse, in my next book, What Stirs Within (science fiction) is physically fit and loves to run. This reflects my own love to run and workout.
All my key characters are vegan. This is something I keep very understated in the writing. Slayde in Loveweaver was horrified as a child when he had to kill a rabbit, so never again ate meat. That's pretty much all I say about what he eats. It's enough.
We all write for the same reason. Because we have to.