The short answer is that he doesn't know what he is doing. The $100m loss is way too much, and I believe he is the worst loser in the history of trading. I wonder how greedy and emotional he was to take such a huge risk in trading.
For me, his greediness isn't the main problem. His issue is that he hunts his primary choice without making any prior decision, even if he sees that things are not going as planned. It's as if he placed an order and forgot about it, which isn't the case here. However, his obsession with closing his trades at the levels he was set from the start drove him to a great loss.
Many faults could be attributed to this, but I tell you, Greed is the major issue here if you think it through. How can someone lose $100m in a trade if not for greed? Even if he is the worst trader in this world, but not greedy, he could have used 1/4 of that risk or lower. That risk is even way too high for reasonable trading. Those who have such a big amount might even use 1/25 of the risk or lower. Is that not greed? Other faults can be linked to his unprofessionalism in managing the situation when it has gone south.