In the sequel novel, King states the book is about alcoholism. I believe that was one of the reasons King didn't care for the film, because it didn't touch on this subtext to his satisfaction.

The book is a very different matter, King always hated the film, and had a TV adaptation made which stuck much more closely to his vision, alcoholism and all.

Kubrick is operating on a higher level, and simply used the book as a jumping off point for his own philosophical exploration, as well as a narrative template.

I feel the film is, to some extent, about fate. Note the scene where the ghost tells Jack that he's "always been" the keeper of the Overlook (I forgot the exact word he used instead of "keeper"). And then, at the end of the film, there's that Steadicam shot toward that unbelievably creepy photo from the Overlook from decades ago, revealing a man in it who looks exactly like Jack. Kubrick seems to be telling us that Jack is fated to go crazy that winter and do what he does.

A well-documented theory is that director Stanley Kubrick departed from Stephen King's novel. "The Shining is not really about the murders at the Overlook Hotel. It is about the murder of a race - the race of Native Americans - and the consequences of that murder." Read on... http://www.drummerman.net/shining/essays.html

Another writer shoots down some of this Indian theory: http://faqtheshining.blogspot.com/2009/12/indians-in-shining.html

Review of another exhaustive analysis is here: http://nofilmschool.com/2013/05/seriously-exhaustive-analysis-the-shining-kubrick

An interview with Kubrick about the film: http://www.visual-memory.co.uk/amk/doc/interview.ts.html

I always thought it was the falling apart of a family. While they had demons it was Jack giving into the drink, Wendy not leaving him and Danny being abused that caused it's collapse. Jack wouldn't get help.