It still doesn't answer the other question, why hide all that money? If you've got the billions, why not show them off? Or if you can't enjoy them, why bother embezzling them?
I don't like to get all conspiratorial, but have you read 'Confessions of an Economic Hit Man'? If half of what Perkins writes is true, then maybe it wouldn't be so hard. He says that there is a parallel economic system in operation that most of us don't know about. If you were part of that world, you probably could flaunt your wealth... you just have to be sure it's hidden from the population at large.
I mean come on, for $65 billion, you could buy Oracle, Goldman Sachs, Boeing, or Apple (in 2006).
http://www.forbes.com/lists/2006/18/06f2000_The-Forbes-2000_...
Or try spending it on stuff - the most expensive house is ~$120 million (Mittal's house next to Buckingham Palace in London). The biggest yacht is ~$100 million. The entire "World" development in Dubai (http://en.wikipedia.org/wiki/The_World_(archipelago) ) cost $14B, and it's selling to some of the richest people in the world. You could buy every superlative in the world and still have most of your money leftover. When you get to that much money, the only thing you can't buy is bragging rights over the people above you on the Forbes list.