Edit:
I get the point others are making about celebrating a milestone and your first sale being the stepping stone to the next, but I don't think it addresses mine:
Is $1 that you made just yesterday really enough data to demonstrate to others what to expect? Is there really any conclusion that can be drawn from such a small experiment? Maybe it's just me, but I feel like there would be much more interesting insights to discuss after waiting more time or when more sales occurred.
Honestly this looks more like an SEO piece given the keyword rich external links in the article from a high PR domain and boost from HN. The author has mostly just submitted his own articles on HN to boot.