because this has always been like this!
when bitcoin goes down => altcoins go down also
when bitcoin rises up => altcoins go down instead

reason? i believe it is mainly because the money always goes back to bitcoin which is the only coin that everyone really cares about and believes in when it comes to real investments.

and there is a couple of exceptions to the above rule:
when bitcoin is stable => altcoins get pumped
reason? because during bitcoin stability traders can not make the same profit from it so they go to pump altcoins and make profit

when an altcoin is already on a pumping spree => that altcoin pumps
reason? because you can't stop a pump from happening. when the rocket is launched there is no stopping it until the pump reaches its peak of the bubble and then there is no stopping the bubble burst and the dump.