i think so risky if you Holding bitcoin a long time , may be just 3-6 Month it's good . but , if you already got cheap or profit you should sell your bitcoin , and waiting dump again .
I think that holding bitcoins for a long time is quite a gamble for some because of the unstable value of bitcoin form time to time.
Holding Bitcoin is the type trading just for people believe 100% the future Bitcoin can growth and famous like Gold in present. In first time choose this type trading, we also know this is a gamble and can loss your money any time.