Are you asking to see the books? I should probably assume this is a rhetorical question. Extensions aren't really a money maker since Adobe decided to hide, deprecate, and stop supporting extension developers years ago. I still do it more of as a passion than a revenue stream.
I develop these extensions, but I also use them to make websites and make money. Selling them and supporting them I do more for people like you.
We make more money using our extensions to create web sites than we do selling the extensions. I'd venture to say most of our users can make more using our extensions than we could selling them because of the diminished extension market. I do it more because I like seeing other people's success and contributing to it. That is also why I spend so much time answering all of the questions on this forum.