Because this market is a bubble, and like every bubble sooner or later it explodes, bubbles aren't stable by definition. The only reason Ethereum is increasing, in the top 15 currencies, and also yesterday for a few hours Bitcoin Cash, is because people are converting their cryptos to these two currencies in order to sell them, because instead of BTC, BCH and ETH are a lot faster and cheaper for transactions.
It is exactly what I did last weekend.
Soon it will be a hell for the people who remained inside.
This for the short-medium term, for the long term (2/3 years) I am very positive like everybody else here.