It certainly came to no surprise to me that the customers who give you the least money cost you the most. The article refers to customers that choose the cheapest option for your subscription service/product. In my experience this also extends to the lowest paying projects for a contractor as well.
If you have a product the article above has a number of tips to try to make your lowest paying customers cost you less. I think that every product needs a set of video tutorials that cover every aspect of the service and written blog posts to match.
Forget the notion that you’ll just build it right and people will figure your interface out. You won’t. They won’t. At least not enough to skip the full documentation and training for the product. I think that many designers and developers talk up their revolutionary ‘easy’ interface simply because they can’t be bothered to do good documentation.