This is because of the cancelation of the hard fork those who were supporting the split have sold all their bitcoins and bought bitcoin cash also Chinese investors want the bitcoin cash to be recognized as the legit bitcoin so they are heavily investing on bitcoin cash and dumping bitcoin.
But Bitcoin investors are pumping in billions as we speak asubuhi ilikuwa $5500 ikapanda hadi $6500 in less than 2 hours hopefully it will stabilize before the week ends
Another excellent tip. Be smart in how you make trades. I am employing arbitrage starting last week. I have spotted someone who is buying bitcoin at a relatively higher price than the one that I am buying at on the exchanges. Just buy and sell and repeat. Trade smart.