I agree on the "supply and demand" part, but I don't think "whales" are really manipulating the Bitcoin's price these days. To do that you have to risk millions or rather dozens of millions of USD. I doubt people are doing that actually.
We know that there are old early adopters who own around 1% of all coins, it should be still easy for them to cause disturbance if they wanted.
There is more than certain - if Roger Ver or Winklevoss twins would dump their coins price of BTC would crash.
Plus, we have many more unknown bitcoin whales that are not eager to publicly flaunt their prosperity.