Apparently, the reason people are currently selling their coins is because CoinMarketCap decided to exclude the higher prices from the Korean exchanges from their listings. So people saw those lower prices and I guess they decided to sell, and more people see the even lower prices and get scared and sell too.
It's pretty ridiculous if you consider just how fragile and fickle the entire market is. And just watch how this gets reported in the major publications, because I won't be surprised at all if they just say that BTC started going down and everything else did too, without even citing the reason behind it.
Meanwhile, I'm just sitting here HODL'ing. I bet people are going to feel pretty stupid when they realize what happened.