Bitcoin is decentralized and no one can control it. When a large number of bitcoin holders in the market make some money flows, the price may be affected, but not controlled.
Maybe bitcoin won't be controlled, but its price could be, looking at the market cap, it's just $1 trillion, and I would say this is a minimal number for the financial markets. So its being manipulated is certain. It's all a game, where people take money from each other and forget about technology or decentralization, it only makes you lose more with illusions.
Market can be manipulated by big whales and I believe that. Bitcoin is a decentralized crypto but its price is influencing regularly. Many people are losing money here who don't know the basics about crypto strategies. But it is not possible as a single person and I think most of the whales work together for their personal benefits.