There's hardly any investment which doesn't have risk, almost every investment has a risk factor attached to it some may have low risk others may have high still others may have very high risk and hence they are very high risk investments. Since the prices of bitcoin are highly volatile so the risk is high too but as bitcoin has a tendency to go up in value and prices it's better to buy them when the price trend is downward and sell them when there's an upward trend in the prices. So buy bitcoins only during the period when you see a downward trend in the market and then you will surely make good profits with it.