yes bitcoin is really secure. if a hacker have high skills in many aspect like programmers, able to break the code, security, and the others and he is not alone, then maybe bitcoin can be able to hack. but so far, the system is secure and until now, no one can break the code. i believe that in out there, many people as volunteer will make sure that the system can works properly without any attackers that could break the system and they are in all over the world and not in just one place. i don't know about blocking p2p system because i am not too understand with this but as we know, once the transaction is made, no one will know for what the transaction for. maybe the government can blocked the connection to connect into bitcoin port but trust me, people will always search a new way to gets connect to the server again especially if that person/people is using bitcoin which is really worth.