The statement about decentralization is very true, no one will be able to control the price of bitcoin. But for people who say tomorrow the price of bitcoin will hit $40k, $100k or some other price it's just a prediction and the predictions made won't actually happen, maybe just close. It all depends on Fundamentals and depends on supply and demand.
Whales also can not fully control, but wahles can do a lot of manipulation to influence the price.


source: https://dotnettutorials.net/lesson/supply-and-demand-trading/