Is Persistence Always Worthwhile?

I've been working on a book for the past six years. I started writing it when I was living out near Chicago, during my years working at VeggieTales. I wrote most of it while sitting in a coffeeshop in Wheaton. I don't drink coffee myself, but the shop was mostly empty, there was a nook out of sight of the employees, the chair was comfortable, and I could buy some hot chocolate every once in a while to keep my sugar levels up.

Over these past six years, the book has progressed in fits and starts into a fairly weighty tome of about 1300 pages. It still isn't done yet, and I guess it needs another 200 pages to finish (that is, if the characters behave the way I hope they behave).

And after it's finished? Statistically, I have a slim to nil chance of getting published. Even if I do get published, the odds are that I will make next to no money on the blasted thing. From a sheer hours to dollars perspective, writing that thing for the last six years will probably prove a wretched investment.

Still...some things you just have to do, regardless of the return.