When price drops over and over everybody thinks that is bad and their invesment is going to loose or they already in loose. Generally this causes loosing hope to that coin, and people generally sell and exit from market.This maybe great for manipulators because they want to control market. right now there is a resistance to manipulators and this causes manipulators to gain less. they earn with volatility and it is decreasing as you can see in yearly graph. so best option for manips is reducing volume so that they gain more control. And for to reduce volume they create hopelessness by lowering price. When you see price is going well to high points you feel better but they cut your dreams with a steep fall like just a few days ago. investors sells or waits that cause reduced volume. And when the volume decreases they can ride the price easily.
Obviously they want big profits, i think to control a market is not easy and i think you will needs so many coins to control a coin or market. It's like a group of rich people that have so many coins and they can control the price easily, just pump and dump and the market will follow them. I don't know people like that is really happened or not though.