They expect every article to make a sale, and when they see no sales from their first 5 articles they give up.
This goes back to old habits. In a job, we get compensated for the time we spend and the work we do. If we work an hour overtime, we expect to get paid an hour overtime and we usually get compensated in the end.
For a business, it doesn't quite work like that.
Article marketing is constantly becoming more of a zero-sum game. If you get traffic, somebody else doesn't. This is inherently due to the more competitive nature of the game now.
This is not to say you can't get traffic which will rack up profits for you from article marketing. But you have to realize that article marketing is a volume game.
You can't expect to make a living out of 10 articles or maybe even 100 articles. And even if you pulled in nice profits for 100 articles, do you think that is going to last a year down the road, let alone 5 years? New competitors will come, thousands of articles are added per day to compete directly with your articles. The well is not drying up, but you've got to maintain a competitive advantage.
And that is to employ a 'big picture' thinking of your business model.
Don't think of 100 articles. Think of 1000 articles.
Don't think of 1000 leads. Think of 10000 leads.
In society, people often deride you for 'thinking big'. But you'd want to think big if you want to break away from mediocrity.
So don't expect to make money from every article to write. Think of the big picture of your business model and how article marketing comes into that.