Its just one component of the financial system though. Instead of breaking thoroughly researched , tested and monitored systems... people who hack banks typically just crack/obtain some manager or admins passwords.

Banks get hacked all the time, fraud happens all the time. Few people will bother trying to attack a component IBM has likely invested 8 figure+ sums in securing. Not when you can sploit a vulnerability on a crappy website somewhere, get 10k credit card numbers and turn em into cash at about a 40% rate from your local mobster. (especially if you are in Eastern Europe)

Or 1000 other simple schemes usable by anyone who can use a canned script, and has a way to launder money.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)