And also, I think the reason on why bitcoin price comes down is because of forking. We all know that there is some speculation that Forking with Bitcoin will happen and I think that is one of the reason on why others tends to panic sell.
How do you know this hasn't happened yet? 
It could of happened days ago when the major pump of the big alts happened few days ago started happening and still are continuing to rise above btc price still.
