[angelbob]

At his price point, he'll probably get a continual trickle of customers. I sell a book called "Rebuilding Rails" -- not as successful as his, but I've also made a few tens of thousands of dollars, so not nothing. And I reliably make a few more thousands of dollars yearly, years after I wrote it.

After Ruby is a "hot" language (years ago), it becomes a legacy language where companies will pay money for assistance with their products. In the $10-$15 niche, you need individual engineers to think a language is neat. In the $40-$10,000 niches, you need companies to think they can save some engineering time.

Both can be very valuable.