The biggest risk of using Bitcoin is it's price. It's price is unpredictable anyone can't guess the future price of bitcoin it will lose or dump you can lose and earn from it but it is risky.
If you plan to hold bitcoin for long term then it is not risky at all. Bitcoin price will grow over the period of time. Only if you are short term investor , then you may may to face some period where price may corrects to 30 or 40%. Also when more people use and adopt bitcoin, this volatility of bitcoin will be far less.