I think many have been sitting on sidelines waiting to either get back in or put toes in water for first time....there has been a lot of media speculation of investment firms getting involved with retail sector at some point....if it becomes real....people don't want to be left out...I also think a lot of "big boys" have been slowly accumulating in anticipation of retail firms coming on board....The Facebook hype just adds fuel to all this fire and adds "legitimacy" at least to Bitcoin....
Also...the restrictions placed on USA customers by Binance and Bittrex have also lead to many of us begin to liquidate out of those exchanges and move into the big three coins....BTC, ETH, LTC.....
Very good points I had not thought about the alt coins being pulled out of those exchanges and most likely being filtered into bitcoin to transfer.