The main problem of Bitcoin is its vulnerability .. by that i mean it is too easy for a skilled hacker to take out coins from people who are new to it or even average users too and when looking from the other side it is also vulnerable as the rates literally fuctuates about 40% every month ..this is something that is beneficial for the people who are into trading but for the rest of the people who use it for other purposes rather than trading might have to face the worst circumstances.