I think that market is down just because of too much selling orders and less people buying it. in current market condition which was already bearish from last top in December 2017, selling send us to downtrend.
Price fluctuations are not just bitcoin, but just like other fiat money is influenced by several factors, such as political temperature, a country's policy, to the negative sentiment caused by a currency's rise or fall, whether fiat or digital. When referring to bitcoin prices in December 2017, the trend is decreasing. Maybe now it's time for bitcoin to correct prices.