They can (virtually) predict the next movement of the market. I mean candles are one of the indicators widely used in the market now a days. If its green candle then it means lots of volume is turning into it and it time to get ready for the sell. If it is red then people are going to sell or dump heavily and if you want good opportunity then its time to buy more at that point. People also make it vice versa to earn whatever profits that they have gotten. Apart from this they do not give much information and reference purpose only (thats what I think of them). Its fun watching them as you get filled with adrenaline when green-red candles are moving.