As Maggie indicated, writing for many is a hobby that can be pushed aside by the needs of life. Being in that same situation, as Maggie is, I can well imagine the day when I just don't have time to write, if life's demands force my hand.
@ Astra, I agree that most of the best books are probably written by inspiration. But inspiration doesn't always make for a good book, and regular payments can be a great incentive for creators, so I do not divorce paid writing and quality. Are you honestly saying all writers who write for a paycheck are not worth reading, and should just give up their trade? Or that all non-professional writers who happen to get an inspiration are great? I wouldn't.
Also, many writers write for themselves, not for others, and do not have as much of an interest in being published. (I wrote for 10 years before releasing any of my books... I was having my fun writing them, not selling them.) Who knows how many good books are sitting on the writer's shelf, because they do not see the likelihood of making a profit, so they won't bother to get it published? Money could be keeping good books from you.