The problem of supply and demand, when all want to buy a brand of milk, the brand of milk will be reduced in the market, then the price will certainly rise, but if this milk no one to buy, be put back to the supermarket, the longer nobody buy, Then the price will be low. So when many people want to buy Bitcoin, but there are only so many bitcoins on the exchange, the price will definitely fall. When the whales sell their bitcoins, the exchange will have more coins and prices will naturally fall. .