It's just another periodic correction. Most of those altcoins are derivative of Bitcoin, so when it drops in value, so will they. People said it was the end for crypto when Bitcoin dropped from $1200 to $200. The smart ones (which didn't include me) bought a load of it at that price and saw a 15x ROI on Bitcoin's recent $3000 high (if they cashed out). It'll rise again to a new high. Just give it time. The worst thing you can do is panic and sell at the wrong time.