What is money, these days? We may have still physical money, coins and notes, but the majority of today's money exists digitally. Digital money is nothing but ones and zeros in large complex computer systems, which transport 'money' from one system to another through transactions. This is a hacker's Valhalla.
Physical bank robberies still occur, but digital robberies are far more interesting and potentially lucrative. Financial institutions are well aware of this and rightly take IT security threats extremely seriously.