Someone keep btc for profit, someone keep the future, some people fear the crisis $ devaluation ... so bitcoin will be a complete choice for them, can trade many countries, Useful quick.
Although these people use Bitcoin to get rich, I wouldnt want to suggest it to anyone that is looking for a 100% sure method to getting rich. Bitcoin can get really expensive or really cheap depending on how many people want it through an exchange. Order Books within exchanges are what the price of Bitcoin is right now, if there were no Bitcoin exchanges then the price of Bitcoin would only be a used as a barter system based on something that someone says.
Bitcoin is one of the currencies that dont really need USD to allow it stay useable.