I think the main reason is the sharks in the crypto market. They have the power to decide the price of the altcoins. So they can make a lot of profit from the trading and increase and decrease the price of the altcoins. They make small traders fear because of the cost of going down and forcing them to sell all their coins to secure their assets. and the sharks would buy all the coins at low prices and sell them at high prices.
I agree with you, they are the one who controls the market price and they are the reason of people who panic selling when theirs a big dump going on.