I also do not know for sure what the cause of bitcoin prices this year continues to decline, may also cause many bad news about bitcoin so that investors choose to sell most bitcoin owned
This is a some kind of a manipulation towards the price of bitcoin by banks and whales, And because of the price so much down right now many panic seller have sold their bitcoin to fiat or other currency, Well that is what I have known many whales wants to buy cheap bitcoin that is why they have manipulated the price, well I really think it will soon recover so change your other coins to bitcoin.