You can't underestimate bitcoin's security or how hard and complex it is to override the smart contracts that define bitcoin itself , it's transactions and it's uses . So unless that person doesn't have access to at least 51% of bitcoin's overall value , he really can't change anything or hack anything in it . And the problem isn't really if some guy hacks into it , the 1st step to the whole thing is the world accepting it and recognizing bitcoin as a official payment method which isn't likely to happen in my opinion (at least for the following 10 years ) , since there's a lot to correct and make stable in bitcoin's features especially the fluctuation . Only then governments and markets will fully accept bitcoin , and this is for holders the ultimate dream .