To publish your own book with proofreaders and graphic design often costs more than 6000 dollars and then no marketing is included, which costs a lot in itself… An ordinary small ad in a magazine that people throw away after barely reading costs between 2-3000 dollars. I have had that experience before and realized that such ads are often a waste of money.
The marketing value of a book never disappears, and you can always refer to what you have written in the book and add the title author in your CV and on social media.
The projects are arranged so that each author writes a chapter of 3000 words which we then have an editor who goes through the grammar and comes up with advice on how to improve. 3000 words is something that is possible to actually write. You will after that be able to refer further so that the reader can read more on your website or social media