Each individual (traders, investors, etc) sales conclusion but whales have the upper hand since they accumulated enough coins which would impact the market price.
Whales have upper hand because they have more funds for bitcoin, you can see how Grayscale really impactful to bitcoin marketcap recently, and recently it has accumulated over 500000 bitcoin, this has been one of the factors that drives the price of bitcoin up right from $10000 to $18000 recently. Although, there are many whales which are regarded as institutional investors, and they are more responsible for the price increase as they buy more than retail investors.