I assume he means failure from a financial perspective, given the OP was asking about writing books specifically as a form of income. I have largely the same st

I assume he means failure from a financial perspective, given the OP was asking about writing books specifically as a form of income. I have largely the same story, I wrote a tech For Dummies book that sold a few copies but was largely a flop. Overall it was definitely worth it from a CV perspective and as something I can say I've done in my life. But we only got a small advanced (I cleared $4.5k) and then never made enough in royalties to get out of the advance hole. So if looking at things purely from an income level it was a complete failure. But of course there are a lot of decent reasons to write a book besides the money.