Every kind of trading is risky. Bitcoin has a very small market cap, so fluctuations are frequent. Bitcoin is often considered one of the most attractive currency for trading, due to high volatility. But there can be a risk of scams and fraud. So choose wisely.
Market capitalization of Bitcoin is nearly USD 20 billion (USD20.000.000.000, source: coinmarketcap.com) as of now. That is not VERY SMALL!
Highly volatile and risky yes, that's why exciting for risktakers. Though its volatility is kind of decreasing IMHO as the market grows. Scams, fraud and crime are not unknown also with FIAT currencies.
