While I agree with the overall sentiment of the article, the hypothetical monetization numbers in the last paragraph are just ridiculous. Getting 20% of a free userbase to pay anything is extremely high. ~0.2% to 2% sounds like a more likely number, based on my admittedly cursory knowledge of monetization of apps. $5 a month also sounds a bit high for essentially a photo-sharing service, a yearly charge of ~$20 sounds more likely. However, for users that have passed the "willing to pay anything" barrier, the actual cost might not as big a deal.

This also completely ignores the viral nature of these types of services; people are more likely to use Instagram when their friends are using it. Without being free, it's not clear whether it would have taken off enough to gain 2 million users (or whether it could keep 2 million after the remaining 98 million left).

That said, I'm all for paying for services, and much prefer that model to ads. But just because some of us would prefer that doesn't mean it would have been the right choice for Instagram. It's easy to look back and say "they should have charged users," but we can't be sure we'd be in a place to analyze them if they had.