Asia still dominates in crypto-trading by volume, accounting for the vast majority of money flowing in and out. Guess what is coming up in 3 weeks? Lunar New Year. Lots of money is flowing back to fiat to buy presents and plane/train tickets.
People spend a TON of money on travel and presents during Lunar New Year. This is their Christmas. This is also the largest mass migration of people on the planet, occurring over two weeks. Projections are for $100 billion USD in spending. [https://www.forbes.com/sites/ywang/2017/01/26/worlds-largest-human-migration-begins-chinese-new-year-2017/#3a6d5502999a]
Remember that the crypto market is antithetical to the stock market. Stocks boom when business is booming during the holidays. Crypto investors are retail investors, not Wall Street investors. Retail investors sell during holidays, thus the crypto market falls.
This selloff has happened exactly 3 weeks before Lunar New Year each of the last 4 years.
Evidence: 
[credit: u/Secruoser]
So, everybody chill out for a week, the bulls will be back by February. You can't fault these Chinese and Korean bros for taking major gains to buy some cool shit for their families. Hell, if you want to, buy up their cheap coins in the meantime.