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.
Don't you think you're only exergeratting with the instinctt that he placed a trading order and got lost of himself? I think before he must have turned such thousands of $ into millions of $, he must had been a professional traders shouldn't sleep off while in the market. If not, he must had traded with greeds hoping to maximize his profits. Probably he tended to take risks significant risky trading order that he hasn't applied in his trading experiences beforenand then it failed him as planned.
As for being the worst loser in history, I doubt that he is. Many others lost huge like him but are not known since they don't post their trades. Of course, the same goes for winners.
Definitely he can't be the worse looser in the trading history since there hadn't been a data comprising of the details of worse traders or losers. Perhaps there should be others who're worse but doesn't disclose their trading outcomes to the public.
Or Maybe there had been but we haven't come across it.