Because Instapaper is an ongoing service, as opposed to a game you download once that doesn't require updates, users represent a continued cost to Arment. Even over time, he doesn't feel most would add up to $3.50 worth of ad impressions.

There is a real disdain in Arment's post for the users who prefer the freemium model. He notes that these "undesirable customers" often leave more negative reviews and this is the primary reason he's staying out of the Android market.

What really seems to nag Arment is that the free version was, intentionally, inferior in many ways to the paid version. He didn't see a lot of conversions from free to paid users in order to access the additional features. "I don’t think it’s a net positive for my mediocre free app to show up next to my great $4.99 app whenever anyone searches for Instapaper in the App Store."

Grabbing just 1% of the market would net Instapaper around $5 million in sales, a number Arment says he would be more than satisfied with. And he ends by encouraging young developers to take a similar risk, even if they don't have a popular blog or an app with tons of press.