Researching and writing help clarify your thoughts, which could pay dividends in other ways. I'm retired, don't need the money and am told old to care about fame, but I have several ideas for non-fiction books I'm working on. Now that I think about it, his blog post presents a strong case for not writing a non-fiction book for money. There are other ways to spend your time with a better chance of making money, unless you're clever self-promoter that is.

"A 98% drop in sales after the first year, Seventy percent of traditionally published titles fail to pay out a single dollar in royalties, Vanishingly few nonfiction books sell even five hundred copies"