acquired Instagram in the spring of 2012, the photo-sharing app had rougly 50 million users and wasn't making any money. The fact that Mark Zuckerberg decided to shell out $1 billion for the rising competitor was greeted with skepticism by some, while others considered it a smart move to step in before Instagram really took off. In hindsight, the latter were right as the chart below illustrates.
The photo-sharing app reached 800 million users in September 2017, its advertising business hit the ground running
and Instagram Stories has become Facebook's first line of defense against Snapchat
. One can only imagine how much Instagram would be worth today, but considering that (the much smaller) Snapchat’s parent company is valued at nearly $18 billion, one can assume that Instagram’s acquisition price was a billion well spent.