I've been approached quite a few times over the decades. In my opinion you will make very little money from writing the book (unless it is a rare O'Reilly bloc

I've been approached quite a few times over the decades. In my opinion you will make very little money from writing the book (unless it is a rare O'Reilly blockbuster) and it will take a horrible amount of time. I think if you do the calculation based on expected income versus the time required to write the book, it is likely be close to minimum wage. Or it sure seemed close when I did the calculation for myself. I think that those books make money for the publishers, but not much for the authors, especially if you can make market wages in a major market, or possibly more if you can get stock or some other form of potentially lucrative compensation.