Blockchain system exist to combat greed and middlemen and to give individuals ultimate control of their identity and activity. In a blockchain future, we will see a world where our medical records are immediately available if we are in an accident; where online voting was possible; and where transparency was paramount and greed is disincentivized.
Essentially the middle man is another human, and humans are the most unpredictable kind of beings. We tend to trust machines and technology a lot more, and rightfully so. In Blockchain, you are putting that trust into cryptography and transparency. Transparency allows everyone to see and verify the rules, while cryptography ensures it does not get tampered. To verify something, a large number of nodes must all agree, which means they will outnumber any potential hacker. Thus, Blockchain is very hard to hack.