Bitcoin drops the price because no one buys and sells it a lot.
The law in cryptocurrency trading is like that, many who buy mean the price goes up, if a lot of the selling means the price goes down.
People tend to put the whole thing on manipulation but in the real sense, if there is a strong demand for the market and a lot of people are adopting it hugely for what it is and not just based on speculations and greed, then there is no form of manipulation that even the whales will not end up regretting.
There is a lot of FUD in the market, and they will keep taking advantage of that until there are no more weak hands in the market. Supply is apparently more than demand and we all know why that is.