The only people who can really manipulate Bitcoin's price would be powerful people in the media. For example, Trump could say something about Bitcoin, shoot the price up, or say something to shoot it down.
I think we cannot manipulate the price of bitcoin because their are site or manager that can manage the price or value of bitcoin. But we can own bitcoin.
I think only people who have many btc who can manipulate the price because he can raise and lower the price.