My father was a writer, and I'm a published non-fiction writer myself. I think the best way to explain the compulsion to write is that writers possess both a deep love of language and the imagination to come up with stories to tell, information to impart, or subjects/issues to be investigated. When you have both of those things, the desire -- the need -- to write comes naturally.

Most writers don't make much of a living from it, which should be an indication of just how strong the compulsion to write is. Most of us have other jobs, such as teaching, which is what I do. My father was a newspaper editor.