If you keep your private keys in computer, it's hackable

Since bitcoin use computer also hackers. I think yes because there is nothing impossible in this world.  Perhaps we can prevent this hack thing by choosing trusted wallet to store our bitcoin, and make a strong password and also make dual authentication to prevent hacking.

Short answer yes somebody can but it will never be worth their while. It would take hundred of millions to hack network and it wouldnt be worth the few bitcoins you could produce. The other worry is the 51% attack but that

too is unlikely because it goes against everybodys best interests. It can happen but I think it is highly highly unlikely.

in Online system All are hackable..beacuse languages can hack any language.

but it depends of how secure your btc wallet is.

Everything is mostly hackable even NASA has been hacked few times , everything online can be hacked even bitcoins but bitcoins has no central server or is one unit ,so it would be hard to hack it.And if you use a trusted wallet then bitcoins are safe, as private keys are very secured.

Yes bitcoin is hackable, because everything in online are hackable ! But it's btc dear, They are ruling the world , so i think btc system is so secure and the best and best hacker teams are working hard to protect btc from any hackers. So, don't need to be worry. Just keep earning the BTC 

May be it is hackable because it a crypto currency and all functions are controlled digitally so one may hack them.
What i think is that BITCOINS very secure because it has a best team which is working to prevent hacking of it. It has been governed by many team members who have eye on it all time .

It extremely safe.

 As far as i know Bitcoin itself and most of the other cryptocurrencies, have never been hacked or even really had any downtime. Even everything is online, it doesn't mean that everything can be hacked, otherwise you are a multibillionaire and can afford to build supercomputer with incredibly huge computational power, beeing a person like this you will not need this. The only way it is unsafe is carelessnes of people.