What about Zcash then? Done a 25x this year while bitcoin has just gone down and sideways
ZEC, some privacycoin and Hype are among the alts that have gone up this year despite BTC trending down. But those are pretty rare cases, and only a handful of alts have managed to do that. Most of the rest still move with Bitcoin.
Just look at the past few days. After that strong run up, Bitcoin is starting to cool off and as you can see, ETH and most altcoins are back in the red.
The overall market trend is still driven by BTC, not anyone else.