What Would Prevent HijodelCid From Attempting Such A Reckless Crime:

The realisation that, if he pulled it off, he would no longer have a moment's peace.
Obviously such a big robbery--something far beyond robbing a 7/11--would attract the attention of every police agency in the world. Everybody in the world would be looking for him in every corner of the planet. His loot would be worthless because he would never be able to spend a cent of it.
The Jackal in DAY OF THE JACKAL says that any hitman who assassinates De Gaulle will never be able to work again. I'm afraid it would be worse than that; the Jackal would never be able to escape the long arm of the law; the rest of his life would be spent desperately searching for a place of refuge--a place he would never find.

God is subtle, but He is not malicious. (Albert Einstein)