This year is worse year for the bitcoon.The drop in the bitcoin is due to various factors like some country made it illegal tender ,other main reason for the drop in bitcoon is that there are some people in Japan having largest amount of Bitcoin sell a huge amount of bitcoin and the last reason is that on 5May 2018 a decision will be taken in country India about whether to legalize it or not.
These reason make a huge impact on bitcoin market and price of Bitcoin drops