Like those ten million writer monkeys (each on a typewriter), ten million image maker photographers (with their 100+ million cameras) will have an equal number of reasons for their reasons for doing what they do.
Me, I alternate between two distinct and separate goals, intentions, points, purposes, reasons. Whichever.
The perfectionist (the architect) in me seeks to record beautiful buildings, mostly old and dating to the colonial era in Asia, for posterity. I enjoy this as I basically see the world and think in grids, and architectural photography further imposes this pleasant and logical discipline on me. My clients (when I sell a photo nowadays, which, alas, is all too seldom) agree with me and buy my images to publish, usually in books. Occasionally I am given a credit as well as a small payment, which further massages and reinforces my ego.
The unorganised (typical Sagittarian layabout) part of me goes out with a camera to make sense of the craziness and at times outright madness of our modern day world. Now and then I succeed. Often as not I return with a digiload of lovely pictures which I post process into lurid 1940s Kodachrome and Ektachrome lookalikes, caption and keyword, and then put away in folders, maybe (or maybe not) to be looked at again or even more rarely, shown to my partner and the few people I know who share my passion.
The main objective of all my photography is to get me out and about and have fun, usually when I travel in Asia, which I do as often as I can. Sitting at home in Australia now, amusing myself by looking at some of my many tens of thousands of old color slides and B&W negatives, waiting for this latest crazy crisis to abate so I can be off overseas again.
Nothing really more erudite or philosophical than that. As the Balinese are fond of saying, "if you think too much, you get sick." Too right!!