Blockchain is not fully hackable and is not that much transparent to the hackers, because data inside a blockchain would be encrypted and would be transparent only to the nodes who are in the networks. Moreover, if a hacker wants to change a record in a block, then it would be notified by each node, since each node has authority for all blocks and the copy of data has been shared to all the nodes. So the hacker couldn’t hack all the blogs and he cant change the record without getting notified by the other nodes.