Why on Earth is anyone showing interest in this self-congratulatory blog post, in which Kun even feels the need to say that he didn't make any errors in the text, just oversights?
The only reason for this book to exist is Kun's egotism. His whole online deal is smug self-promotion, and he seems to lack the self-awareness that would enable him to tone it down. He is a caricature of the arrogant tone-deaf geek.
I have a few books in progress, some farther along than others, and seeing posts like this with actual numbers on revenue is extremely helpful.
After all the work he did, he made about $150k so far. Honestly that isn’t a lot of money for his expertise and the amount of time he put into it - if he moonlighted as a consultant for those hours he would have made more, with less to show for it.
This. You might find @b0rk's post on her zine sales interesting: https://jvns.ca/blog/2019/10/01/zine-revenue-2019/
The majority of sales (2.7:1) are ebooks. I expect that will change when things get to print.
The most effective marketing strategy for me has been to just be active in relevant communities. This tweet (https://twitter.com/timClicks/status/1154300574151483394) netted me over 300 sales, for example.
The royalties are _far_ less for me than the $15 that Kun has been able to achieve, however. Using a traditional publisher achieves about $2.5/sale for me. Although the retail price is $40, it's often heavily discounted. I have 0 influence over the price sold.
Also, it's quite interesting to see actual sales figures. Most authors tend to be shy to reveal numbers.
1. You think you can explain well-known material better than everyone who tried before
2. Your field recently exploded, and you feel that you are the contributor most suited to converting the papers into a book
3. Your field is solitary and obscure, but you think your papers need to be collected into a book
I like textbooks! They generally put in effort to unify the notation and find connections between papers, making it easier to learn the topic. I'm glad some people are egotistical enough to write them.