According To expect they always say blockchain can never be hacked and your information can never be stolen .. But day in day out Hacker are hacking crypto exchanges to steal people asset , ETH Suspended hard Fork because of security reason . HitBTC and Cryptopia are understand maintenance because of hacker . Are they Using block-chain technology to deceive Us ?...
How could you possibly say that if there are billions and billions of dollar circulating through block chain? Well, yes it is still vulnerable but think of the bright side such as it just need many hashpower and it is strong enough.