We had 13 employees when Facebook bought us for a billion dollars. Everyone said we sold too cheap. They were right.

Instagram was always about one thing: making photos beautiful. The moment it became about everything else I knew it was time to leave.

I studied photography in Florence. That semester shaped Instagram more than any computer science class ever could.

The best products do one thing perfectly. Instagram did photos. Then it tried to do everything. I still believe in the original vision.

A billion users chose Instagram. Zuckerberg chose what Instagram would become. Those are different choices.

Leaving Facebook cost me billions in unvested stock. Staying would have cost me something more important.