I’m not sure if this falls under your definition of “technical books”, but Michael Hartl’s Rails Tutorial is an incredible example of a 1000 fans-esque type of

I’m not sure if this falls under your definition of “technical books”, but Michael Hartl’s Rails Tutorial is an incredible example of a 1000 fans-esque type of (light) technical book. That was started in 2010, and for a long time the online version was free (he made money from videos, pdfs, etc. He has since expanded his library. He has many fans, and makes quite a bit of money from his projects.