Sometimes many people try to manipulate the market and buy precious tokens cheap and selling high later.They intentionally cause fear and panic in the inexperienced members and take advantage to perpetrate their greed activities.
Those that have the power to manipulate the markets are going to use it, even if they do not want to use it they cannot avoid to manipulate the markets even if they wanted, if a group of rich people with tens of billions of dollars suddenly decided to invest in this market that will obviously make the price to go up, so they are manipulating the markets but no one complains when that happens because they earn money, but people with that kind of capital may decide to short bitcoin or to sell their coins and this will make the price to go down and that is when everyone complains.