The way I see it, it was not only bitcoin that went down, all crypto currencies did.
Most altcoins evenmore than bitcoin. Only the price of ETH is now about as high as six weeks ago.
In fact, no. Bitcoin and the rest of the crypto market are EXTREMELY in sync. Even though the market crashed near 50%, bitcoin's market share has remained in the 33%-35% window. That's hard to explain, unless there's an active regulation mechanism: are ALL altcoin traders keeping all the time 1/3 in bitcoin ?
Some alts go up, others go down, but bitcoin remains at a very precise 1/3 even though everything shakes for 50% or more. Incredible.