The flip side to opportunity cost is the hidden benefit of launching a successful ebook.

It's SO not just $15k.

Think about all that crippling anxiety over building something no one wants. Or the psychological wounds still bleeding raw from a product attempt that failed for whatever reason.

One small step in the bank statement, one giant leap toward 37signals.

This is why I made the point about killing my other "product". I had nowhere to go with it. Perhaps I didn't say it well enough, but my initial plan was to build something but the problem wasn't marketing, it was that nobody wanted it.

My book, however, people want. I looked for what developers need first and then built a product around that, rather than thinking of something that might be nice and try to get people to buy it (like my CMS hosting).

There is more to success than the income.

1) You build a mailing list of people who have bought from you in the past. HUGE value here.

2) You get some extra personal brand exposure. Invitations to speak at conferences, podcast interviews, and so on.

3) Passive income is the gift that keeps on giving.

Good points but don't forget that he probably also increased his expertise in Ruby which itself drives value in his consulting work.

Not necessarily.

But it certainly increased his percieved value.

Is it a false dichotomy to assume he could have made the same $15k doing something else in less time? $15k is still $15k, and it's likely that had he opted not to write the ebook n+6 months ago he wouldn't have earned any additional income.

There may also be some non-financial benefits of going through the experience as others have commented, plus the sense of accomplishment.

This is a really good question. I actually avoided recording this because I didn't want to depress myself during the writing. I spent a LOT of time on this.

It does, however, come from real-world work. My client projects have been successful from techniques in the book. I'd need to split hairs to determine what time was spent where and in the end I just needed to write.

It's the same problem with choosing a ebook platform. No tool does you any good until you are actually using it. I'm currently writing in Apple's Pages app because it was the nearest and easiest way to just get started.

The benefit of a product is that it can become many things and the hours put into it can be easily won back with more sales.