One can, a la Sigmund Freud, pontificate on one's own childhood and upbringing and rationalize one's own current outlook and motivations. In this, my reply is that I was an only child raised by a workaholic father, which left me with the time, means and necessity by which to entertain myself. Within sight of whatever adult authority figure was appropriated to my "care".
So, I read. Lots. Unlike other (like omg, dude, every) vigorous writer/reader that I know of, I cannot cite great influences. Oh yes, I read Tolkien and Asimov very young, and they linger with me conceptually, in world building and storytelling.
My childhood was also dotted with stage bound performances, acting, and that also remained as a vague theme of something influential (successful performances became validation of self-esteem queries); again, I could not tell you the names of the plays I did.
Back to the question. Why do I write?
In my sin-filled twenties, I was a performing Emcee, a DiscJockey who could sing, dance, tell jokes and run contests. Fame and glory were mine for the taking.
I did not care. I still do not care.
Ladies and gentleman, there is something greater than fame, glory and power (and even slightly better than the women who love the same) - there is satisfaction.
That satisfaction, to this day... let me describe a cheesy scene.
* * *
Winter. Pinellas County, Florida. The Canadian retiree population is there en masse. It is Tuesday evening. Karaoke has started early, with another host, and I have taken over for the night time festivities. The night is still young. The crowd wants to leave, because I am a young kid, and I do not sing doo-wop hits of the 50's. But, I give them a smile, remember their names, encourage them to stay a bit longer.
I am young and full of energy. It pulses. It washes over the crowd like the scent of wildflowers in a midwest meadow. I play music with a heavy bass line and dance like no one is watching. I know they're watching, but that's not why I dance.

I savor their moments with them, I see their little grey heads bob up and down to the tunes of choice. They smile freely, without worry.
The thirty somethings begin to show up. They've worked hard all day. They just need a few drinks to take the edge off. I greet them with a knowing grin.
An hour into a show where people mostly entertain themselves, and I am simply the conductor, the emcee, the host - the energy mingles. The group unwinds. The pulse of energy is contagious, it is a virus of passion, of desire to forget what we think we know.
I see a retiree doing the Electric Slide. Then another. I see the corporate executive loosen his tie and serenade his girlfriend with a horrific rendition of some angsted 90's alternative rock ballad - and the crowd goes wild, and the girl looks about to cry.
One by one, over time, they forget who they think they are, and become something that's okay to be. Unburdened by societal pressures, by the nuances of age. They laugh, dance and smile. One by one, I watch them, encourage them, indulge them, their momentary escapism.
That is my job.
The night lengthens, and reality calls from its faraway corner in the shadows of their mind. Work, responsibilities, budgets. Slowly, some leave. Never without thanking me for this or that. Me, I'm still bouncing around, I'm a jester, a fool without a care in the world as far as they know. But, I drop the mask for just a moment and thank them for stopping by, for allowing me to entertain them.
There is no greater satisfaction in the world, in that single moment of connectivity with an absolute stranger. That I have provided the salve of escapism that soothed the worries of their day, week, life.
* * *
In writing, I can take that one step further. Back to my love of psychology, I can help a reader escape - AND - I can force a reader to think, to consider, to ponder their own what ifs.
In my childhood, that was my benefit from reading. When I read a book, I imagined myself the protagonist, living the world that the author provided, pondering the notions - and for a time, I forgot that I was maybe bored, or lonely or whatever else was on my mind as a son being raised by a workaholic father.
I can do that. I know I can. I can bring the best experiences of my life, the satisfaction I got from seeing that smile; and take it one step further, into unlocking the mind, letting the mind escape.
I create - in writing, in real life - a world where the possibilities are within reach. I provide a window to escape. Sometimes, let's face it, life/living is pure hell. When I see that I have allowed someone to escape their own shackles, I swear there is no greater satisfaction. It is gift given and gift received in one.
That is why I write.