It is nearly impossible to hack the Bitcoin network and steal Bitcoins. You will need to find the private key for a particular public address. The possibilities are limitless. The blockchain behind this cryptocurrency stays steady at the moment, impossible to be hacked or destroyed by any entity. However, it doesnt mean that hackers dont steal Bitcoins - they do it, but not because blockchain is the problem. The problem may be in the exchanges, wallets, and other players that operate with Bitcoins. For example, if hackers attack a website, it does not mean they attack the Internet.