How I Earned $160,000 in Passive Income from Writing Non-fiction Books
In about six years, I have sold over 40,000 books and earned over $160,000 (income) from selling non-fiction books on Amazon, all these while writing from the side.

I have a full-time job, am a father of three lovely young boys, and I don’t have time to spend 40 hours a week writing books. But in this article, I will share with you my journey.
I write mainly tech books:

Thankfully, my readers have been supportive and quite a number left good reviews. Quite a number have been Bestsellers


A few have been adopted by universities as textbooks:

The best thing about my books is the passive income that I get from them, allowing me to have more time freedom in spending it with my family.
It also led me to be more confident in myself, knowing that I can always quit my job and go full time into writing. But I love my job and find meaning from it (i am in christian ministry).
I wake up daily excited to write. When work is a dread, or when something unhappy pops up, some writing will always bring in positive energy into me. I don’t dread writing. In fact, I can’t stop myself from writing!
Besides the income, writing has also established my authority in the tech field. As I have mentioned, universities have adopted my books in their subjects. I have been approached by traditional publishing houses to author books for them.
Here are some mindsets that have helped me get started on being a successful nonfiction author:
1. You don’t have to be an Authority
Yes, I have a computer science background, and I worked in the industry for a few years. But in no way am I an expert in the topics I write about. For example, in my most profitable book, “Beginning Node.js, Express & MongoDB”, before writing the book, I did not have experience in that before. I did have previous experience with older server-side technologies, but not Node. So was that going to deter me from writing a book about it? It can. But learning a new technology itself was interesting to me. So I read the top three selling books on Node, went through the top few online courses on Node, and compiled all that content into my very own compact book (which makes me know more than 90% of people already).
And because I was learning as I was writing, I didn’t have to worry about sounding overly advanced with jargon as I wrote from a beginner’s perspective. An expert sometimes forgets the struggle of a beginner.
C.S. Lewis says this, “The fellow pupil can help more than the master because he knows less. The difficulty we want him to explain is one he has recently met. The expert met it so long ago he has forgotten.”
2. Solve a Micro-Problem you know (Niching down)
I didn’t set out to create the ultimate guide on a particular subject. I instead found a market with many problems and wrote a book for one specific problem. For example:
- Instead of web development, what about web development using Angular?
- Instead of Blockchain, what about Blockchain using Solidity and React?
- Instead of cooking recipes, how about a recipe for a specific kind of diet?
- Instead of Learning math, what about Learning Singapore Math?
3. Piggy Backing Trends
The above topics might still be quite a broad market with strong competition. E.g. React, Angular. To distinguish yourself, have your book address the latest versions of the technology, or address the latest trends. E.g. instead of Learning iOS development, what about Learning iOS 15 development. Instead of personal finance, what about personal finance with NFTs.
In this way, though you as a beginner author is not widely known, the topic you are writing about is!
4. Write Short and Concise Books
This is a trademark of my books where I am straight to the point. I’ve gotten many good reviews for this:


Firstly, your reader will appreciate you for cutting out all the fluff and going straight into the good parts. And a reader can actually finish the book and leave you a good review.
Secondly, you as an author will find writing a short book much more achievable. Instead of writing a 500-page book selling for $50 (which probably few will buy), write a 100-page book (that solves a subset of the problem) and sell it for lesser which greatly increases the number of buyers! (yes, you profit lesser but that’s for another article). At least it got published rather than remaining in the procrastination void. As you spend less time writing a book, you risk wasting less time if your book is a failure. Using Daniel Vassallo’s terms, write a book portfolio of small bets!
Thirdly, it fits in Amazon’s price range of $2.99 — $9.99 (gets 70% royalties for ebooks). Anything lesser or more gets 35% royalty. For a $9.99 book, the word count is around 20,000–30,000 words. If you spend more effort writing and increase the price beyond $9.99, you only get 35% royalty. Why not split it up into another $9.99 book instead?
(Note: the above is for the ebook version. Paperbacks have a different price structure. You can price them higher with higher royalty rates.)
5. Validate your Book Idea
Enter your book idea, book title and related phrases in Amazon to see if there is a demand for it. How do you see? Look at its best sellers rank.

Preferably, it should be < 150,000. This means that it sells 2–3 copies per day. Also, look at your competitors. Ideally, a profitable niche will have good demand and low competition.
Do not be immediately intimidated by niches with strong competition. Firstly, it proves that there is a strong demand for it. Secondly, what are the ways you can undercut the completion? Perhaps write a better book? Or offer a cheaper alternative? When I was researching my NodeJS book, there was tons of competition in that niche. But none had 4.5 stars and above rating. So, I risked it and wrote a NodeJS book. Today, it is one of the best-selling Node books out there.
What’s Next
Okay, that’s all for now. I will carry on in another Part II article. Meanwhile, I will continue to write more books!
You can follow me on Twitter as I continue to document my journey.
*If you would like to embark on a similar journey as mine, and want me to guide you personally on your journey, I am thinking of hosting a very small cohort-based-course (no more than five people per cohort) held over a month with 4 weekly live sessions. In it, I will personally guide you to create and sell your very first book on Amazon (and provide many secrets). It is a very small cohort on purpose so I focus on individual students. If you are interested, you can sign up at https://greglim.gumroad.com/l/author, DM me on Twitter or drop me a mail at support@i-ducate.com.