So the value of bitcoin going from just around 350 to just around 700 dollars in a week is not a bubble? Have businesses using bitcoins doubled? Have users of

So the value of bitcoin going from just around 350 to just around 700 dollars in a week is not a bubble? Have businesses using bitcoins doubled? Have users of bitcoin doubled? While possible, I must say that the chance of people investing in the currency not as a currency to be used but as a money multiplier would be a bubble. What underlying value has bitcoin shown to necessitate a 2x increase of value in a week? I'm honestly curious.