Tax treatment of Bitcoin also affects the volatility
Recent announcements by the IRS stating that the currency is actually an asset for tax purposes had mixed effects on volatility.  On the upside, any statement recognizing the currency has a positive effect on the market valuation of the currency.  Conversely, on the downside, the decision by the IRS to call it property had two negative effects.  The first was the added complexity for users who want to pay with it.  Under the new tax law, users would have to record the market value of the currency at the time of every transaction, no matter how small.  This can understandably slow adoption as it seems to be too much trouble for what it is worth for many users.  Secondly, the decision to call the currency a form of property for tax purposes may be a signal to some market participants that the IRS is preparing to enforce stronger regulations later.  Very strong regulation of the currency could cause the adoption rate of the currency to slow to the point where it is not able to achieve the mass adoption that is critical for its overall utility in society.  Recent moves by the IRS are not clear as to their signaling motives and therefore have mixed signals to the market for Bitcoin.