The pump and dump is a small group of people in the market that destroying the image of a coin do better not to buy a coin that has a surprising move upward in a split of seconds.
those kind of groups did not affect the market too greatly,
but instead those FOMO'er is the biggest reason why Bitcoin and any other cryptocurrency got a huge setback in term of price.
well,it's not the first time those FOMO'er made this kind of action.
just look at AMAZON,GOLD and other.