Literature

Yes. The "For Dummies" books are on occasion prepared and written by people who had no knowledge of the subject and we're self-taught. They chart their learning, do some research, and prepare a guide that is then edited.

Some of the authors are better than others and they become professional learners. Kelly Ewing seems to write about...many topics^ke.

The large majority are written by professionals, like Dan Gookin^dg. Nobody would read a psychology book by someone who isn't a doctor, would they?

If you were to read Tim Ferriss's "4 Hour Workweek", you'll note that he is proposing just this, an "information product". Anyone can be an expert. And, in a way, that book is an example. It is a list of anecdotes and some references. That isn't a recommendation, but if you ever see a used copy or can check it out from a library, the gist can be groked with little effort.

Do you have particular knowledge of a subject? Do you remember how you gained that knowledge? Could you break it down into parts, by imagining you had to teach, for example, a 10-lesson course on the topic? Begin with blogging, build up a following, move on to paid subscriptions, contact an editor and tell them you want to write a book.