the main danger is the unstability of the currency. sometime the price touches high and sometime price drops down to even 90% or less so investor get heavy loss for that.
We need to have a mentality to accept losses too. Important factor with bitcoin is the price varying in respect to time. I personally like the fluctuations, none other than bitcoin has got such feature. If the price is stable we cannot make better profit. Things are dangerous based upon the way we take it.