The altcoins are dumping and crashing, because it might that investers are buying Botcoin and
selling altcoins or people feared that hardforks of BTC on 25 october , and also this situation makes altcoins comes down so not big worry for that altcoins crashing but I think if you have good money to invest for long term, buy altcoin or if have altcoins and that in loss hold it.
People are selling altcoin so that they can get Bitcoin gold and Seg2x.
Usually altcoins price dropping down because of this upcoming hard fork. Actually, this is normal situation of altcoins price but the good thing during downtrend you can collect and buy altcoins, eventually the value will recover. The good time to buy and wait for the price to grow.