My concept of "bubble" stems from over-valued acquisitions, based on everything but revenue. I'm not saying that "Instagram is the bubble". All I tried to do was to put things in perspective, considering a new and upcoming brand versus a very established (and profitable) one.

PS: I did know about Instagram hitting 100 million users… I actually chose to put the number of users at the time of acquisition, as whoever had bought them was bound to increase their user numbers exponentially (if nothing else, for the sheer publicity such an acquisition provides).