This is a different style of trading than what investors do. He said that he was never more than a few contracts in. A single contract needs $10K day trading margin usually (depends on time frame and specific contract, but it's a reasonable estimate). Therefore, if he was never more than 10 contracts long or short at the same time, the risk was of $100K.
Making $500K on $100K over 6 months is good business.
Making $500K on $100K over 6 months is good business.