Governments indicate volatility to be one among the negative factor and fluctuate the market.
It only causes a negative feel because of the fact that they are not being regulated, its market value can be manipulated by those people who are in capable to transact at a higher volume. Also, another reason why the government warns people to take precautions is because of Bitcoin being digital, which is a clear sign that it may only be temporary as no physical sign to support that it will not fluctuate gradually, and the fact that it can be a tool for money laundering schemes.
The worst thing is that many countries have banned bitcoin like my country and this became the reason for volatility in the price. When the good image goes on about bitcoin more people invest in bitcoin and the price rise and when someone gives false statement and create negative image of bitcoin, the people withdraw their money and price falls.