[...]
Too bad that it makes the price nearly impossible to predict. Lines on charts cannot tell whether Bitcoin will be the next TelexFree in Brazil, or whether the US government will change its mind and decide to ban it...
True.
But those "lines on charts" (not really, but technical tools, i.e. various functions of price and volume) tell you what price will likely be in an hour, with pretty good accuracy, in most states of the market. Up to 24 hours, with some good enough precision, usually. Up to a few days, with quite a bit of error. Up to two weeks, with a lot of error.
Not that different from the weather report when you think about it...
Today, maximum temperature in Rio de Janeiro was 21° Celsius, with an average humidity of about 5%. Brazilian geometrists nearing retirement suspect the latest economic development in Costa Rica was the main cause for this phenomenon. ^_^