> When Facebook acquired it, Instagram was a photo sharing app that had 13 employees.
Sure, but it was a serious threat to Facebook with hordes of especially younger people moving away from FB in favor of more activity on Instagram, which at that time had evolved from "just" a photo making/sharing app to a social network.
No. Mobile Camera Apps were a threat to non mobile first facebook. ("Instagram is a photo service in a sea of other photo services.")
Any one of them could have taken off and eaten facebook's lunch. Instagram was the winner in a sea of camera apps because facebook threw unlimited resources into the hip app of the moment.
Sure, but it was a serious threat to Facebook with hordes of especially younger people moving away from FB in favor of more activity on Instagram, which at that time had evolved from "just" a photo making/sharing app to a social network.