Writing on writing

There can be nothing more exciting than someone writing on the topic of writing, well maybe a geometry theorem, but that depends how you feel about math.  My question is, why do certain people 'have to write' when the mood strikes them?  Does this apply to people who collect squirrel figurines, square dance enthusiasts, and people who enjoy memorizing pi?  I was born this way, it is something of an addiction, does this apply to other preoccupations and obsessions or solely to writers?  But then there are times I actually have the time and intention of writing but nothing to write about.  It is only when I 'have to write,' that I can't find the time or chance to do so, then I get all nervous and shaky like someone going cold turkey after getting hooked on some addictive substance.  Do they have treatment programs for people like me?