You pretty much said exactly what I think the cause is. Lots of inexperience, short term, and "get rich quick" investors are cashing out on alt coins to jump on the BTC bandwagon. It should stabilize in the near future but with all the talk about a BTC correction, who knows what will happen. In times like these, it's just best to hold.
I´m just curious what´ll happen, in case the short term investors really get out of the market. It´s very likely IMO, that there will be a drop sooner or later whenever the media doesn´t push the cryptomarket into the public that much anymore...