Altcoins are crashing because bitcoins are increasing. A large amount of altcoins have been traded just to get a single bitcoin. When a large supply of altcoin have been distributed, the lower its value will be. If the bitcoin's value is increasing, the altcoin's value will decrease because lots of investors will trade their altcoins to bitcoin. A large amount of supply of altcoin is traded to a small amount of bitcoin. It is just a supply and demand problem.