This is basic truth that pump and dump in the market of the bitcoin as well as in another cryptourrency  depending upon much to the Rumours and negative news , so it is much easier for a trader to trade if he can expect that when rumour is coming and when it is going and also how much chances is there to get impact by that rumour in the market of cryptourrency .
If Rumour is negative and is against about cryptourrency then surely bitcoin price will get dump and if anything is positive or may be like that will force to increase the use of bitcoin than that will result into Increase in price .
Hope with thee ideas you can make expect that how the price can change to up and down .
And also we should make investment our money in bitcoin when it get dumped and sell when get high because dump us always a time to ignore negativity and make investment