There are several elements that contribute to the success of a money making website, and while sales are definitely the end result, they are not the only contributing factor. In order to generate sales you must be able to get the information to your target audience. If no one knows about your website and what you are offering you will not generate any sales volume. With that in mind it is reasonable to assume promoting your website is a prerequisite to generating sales. However, neither element can stand alone: you need to promote your website to generate sales volume.
Do not have the mistaken idea that once you do the initial promotion and begin to generate some sales volume you can stop