Probably everything can be hacked, or stolen. If we live in constant fear that is not a life, I know how many things can go wrong but that doesn't stop me to spend my time here.
OP said a good thing, don't put all your eggs in one basket. We can`t know will someone hack a blockchain, or will someone rob a bank. Bad things happen and sometimes some bad thing hit one of us. We can`t do much about it, we only can try to protect our self`s the best we can. Always have a exit strategy, or some back up plan, if you think something wrong will happen you can prepare for it.
well you are right, though bitcoins itself cannot be hacked, but people wallets can easily be hacked if they are online