First - It is dangerous if you put all your money in it because only two things can happen: It can either increase your wealth substantially or it can zero all your assets. Hence, in this instance, you have to be wise by not putting all your eggs in one basket. You have to scatter your investments so as to divide possible losses.

Second - It is dangerous if you have Bitcoins already yet you have exposed your accounts to others. In this scenario, the security of your Bitcoin accounts/wallets is at risk of getting robbed. What is more is the fact that it cannot be easily traceable once your Bitcoins have been hacked or robbed from you.

Third - It is dangerous if your country of jurisdiction have made all possible measures to ban Bitcoins. Well, in this case, you can hardly encash your Bitcoins. Neither can you do any transactions involving it.