Kind of how most people who got rich off the gold rush are those who were selling shovels.
I recently found about Tyler Tringas, who has open revenue numbers, is profitable, and specifically focused on making the business as automated as possible to have time. He was going to write and sell a "metabook", but decided against it precisely for reasons of credibility. He's publishing it for free at https://tylertringas.com/micro-saas-ebook/.
Another one is Jason Kester, who wrote about how he did it for free on one simple blog post here: http://www.expatsoftware.com/Articles/guy-on-the-beach-with-...
It's good to see there are some actual cases, and it sounds at least more doable than the crazy startup lottery that is, ironically, more socially acceptable. (Passive stuff is for lazy people.)
A more accurate analogy for 99% of the online passive income people would be that they got rich selling maps for where gold is, except the maps are a complete fabrication.