You make a good point in here. Being a financially successful author isn't just about being a successful writer - it's being a successful business person.
Writing is half the battle—it is a significant hurdle and not everyone can write a great technical book.
But the other half (and I struggle with this mightily) is sales/marketing (and the whole 'business' side). Making it look pretty, getting people to know it exists, promoting it.
Many of the best technical writers I know are not great at the latter, and for them, self-publishing might not be the best approach.
This may not be the forum for saying this, but in case you need encouragement, I always follow your links when they make it to the front page of HN, and I’m always happy when I see your name in the comments. I’m a sample size of one, but I suspect you’re on a good trajectory in term of notoriety. If you struggle with self branding and promotion, you still seem to be doing something right.
