There's too many reasons to look for with these manipulations but if you don't want to stay independent just work for yourself by buying if the market goes down.
manipulations do exist
It really does not only to bitcoin market.
Crypto is not safe when we are talking about manipulations, it begins with banks and financial institutions then go further inside stocks and forex, same concepts with crytpo those who knows how to play with people's emotions can manipulate the trade and the value of every coins inside the market, we can't avoid them so better to learn how to play with them.