Cryptocurrencies have not had a good year so far and the sell off has now accelerated due to rumors that China and South Korea may implement regulations that could go as far as banning trading in cryptos.
Below is the one month chart for Bitcoin. Yep, that is almost a 50% drop in a month. That is what happens when there is no real underlying value and price is set simply by supply and demand. Bitcoin increased roughly 1500% in 2017 and it will be interesting to see how it fares in 2018.