this wave of new pumps came when bitcoin started to go down, many of these altcoins (such as Dash and Eth) used this incident to their own advantage. they pumped their coin and fooled others that "bitcoin has failed" and "we will replace bitcoin" and people are usually greedy, they think since bitcoin could go up from ~10 cents to $1000 then any altcoin can too. that is why they buy in.
just let the dust settle in bitcoin market and let the price bounce back above $1100 and you will see the big scale dumping all over the altcoin market because the same reason why these altcoins went up in first place will no longer exist and those greedy investors no longer have any reason or faith to keep holding and when a nudge comes they all panic sell and the ripple effect will be catastrophic.
Why are we even surprised? Int this the regular norm for crypt? Isn't it 'that time' of the year again?