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 ?...
Blockchain technology is a system use for data recording , if anyone altering the data , it will be recorded also by itself so it's been useless for hacking while the other you mention like exchange firm is really the subject by hackers and yes it will be easier to them if you would not taking care of your private key and password .