My reasons for photographing have shifted over the years. I should try to break it down:
In the 1950s I took a couple of pictures with my parents (and grandparents) cameras. Nice introduction, but I cannot remember my motivations.
In the 1960s I photographed because it was something I was just becoming old enough to understand and I enjoyed the cameras.
In the 1970s it was because it was easier than painting. I was a hippie/student/entrepreneur. What can I say?
In the 1980s I photographed because it paid the bills. From 1976 to 1986 I was a successful commercial photographer, and business owner. However in 1987 I had a crisis of faith, and became an educator, which I have been ever since. Photography eventually became a hobby, but I left it for 10 years, and mothballed my darkroom.
In the 1990s I rarely photographed, but I did revive my painting. Over 100 acrylic paintings and hundreds of drawings. In 1999 I got my first serious digital camera (Nikon Coolpix 950.) Soon, I was back to button pushing with gusto.
In the 2000s I photographed because I was learning something new (digital photography) and because I was intrigued by the possibilities, which seemed endless at the time. I also explored hybrid photography as I got my first scanner, and un-mothballed parts of my darkroom.
In the 2010s, ... ok, it's a habit. I make pictures, always have. I do photography for personal enjoyment and the occasional 'art' exhibition. I keep my real job.
Now I play with the idea of the occasional commercial job, but I get the best motivation by taking the "portfolio development' class at my school. It costs me only $15 , so why not, eh? I get support and critique for a new project every time.
When I break it down, I photograph because it is something that I enjoy. Do I really need another reason?