Novels on average, weigh-in at 300 pages, or about 80,000+ words. That's a lot of dead trees for an author to toil over and for a publishing company to invest time and money into. It may be years, even a decade or more, for a writer's first published book to hit the shelves.
That's a lot of time without any positive cash flow.
Christina Katz discussed how one can earn an income in her Mailbox Full of $$$: Micro-Publishing Your Way from Beginner to Book Deal workshop.
In the Pre-Internet Days, the literary world was divided into two distinct camps: Aspiring Writers and Published Authors. Now, thanks to the internet, along with the shrinking attention span of readers, there's a sliding scale of grey between these two black and white groups.
Somewhere in the middle, is the "Salability Point," where a writer begins to earn money for their work. And this income doesn't necessarily have to be in the form of a printed book either. Other publishing options exist, such as:
--Producing an e-book (50-100 pages)
By writing these short pieces you can develop your skills as a write and build your platform (area of expertise and web presence). Anything you write, could lead to something bigger.
Christina's a firm believer that writers should make money and not be starving artists. However, you may have to start out writing shorter pieces for less money--and then write lots of things for less money--before moving on to write full-length books.
Even when you do decide to tackle writing a book, you have to decide whether to self publish or seek traditional publication. Keep in mind though, traditionally published books are also produced on a spectrum. Not every book will be as successful as anticipated, so budgets are tighter and publishers are pickier than ever on what books they decide to print.
On a lighter note, no matter what we write, we should enjoy what we do. When we get away from our playful/creative side, the less we'll enjoy our writing and our work will suffer.