The author isn't saying that selling is necessary only to make money. At the end of the article he says "But the word "sell" doesn't necessarily mean what you think it means", which then leads to the aside:
"you can either do it in such a fashion that people can indeed build on what you've done, or you can do it in such a fashion that the next person has to essentially duplicate again what you've done"
"you can either do it in such a fashion that people can indeed build on what you've done, or you can do it in such a fashion that the next person has to essentially duplicate again what you've done"