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.

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

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

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