It does not matter if the price goes down, BTC always has a similar behavior at any stage of the market, it is likely that it has gone down because some who enter the market want to buy cheap, this is logical, what this brings as a consequence is for altcoins, altcoins are going down a lot.
The largest of all currencies that will always be trusted and has a life of its own is BTC, there is no other currency that comes close to it, all altcoins depend on btc, that is why alt holders always worry when BTC short.