Re: what could cause bitcoin prices to go up and down?
I want to know what you think, what affects the bitcoin price, so we can find out when to sell and buy bitcoin, because now the bitcoin price drops again 
Mostly because of demand and supply. The higher the demand of bitcoins, the higher the price gets; likewise, the supply of bitcoins become low or high, then the price would be higher and lower respectively. Panic selling and panic buying causes the price of bitcoins to inflate really high like a bubble.