Its amazing how far back into basics I have to go when I start talking to other people about programming. Some of the most fun I've had was helping my brother through his "Intro to C" class. God I hate pointers...
So, that said - maybe it's not feeling like an authority, but more feeling like you have an alternate/interesting/different take on a subject.
Yeah I agree that other perks can outweigh the money; see also the comment below about marketing being one of the hardest parts about writing a book. Getting more known now will help future books I write (Nathan Barry is a good example).
I am reaping some rewards of having expenses covered to do workshops abroad. It's not a source of income, but it does make travel a lot more affordable which is great.
Ultimately, I hope that there will be some long-term passive income from the book (and possibly other books). We'll see. :)
There are times when you start learning something only to realise while there is a definite market for the approach taken by the tutorial site, you expectations were a bit different. There might be topics which the instructor thinks everyone programmer should know. And for a non-programmer it takes hours just to figure out what was the instructor talking about.
That said, for me, this is just one more data point that you don't write a book to make money off of book sales. You do it to establish yourself as an authority and earn from that new position.