I feel that what he's saying is that it's hard to tell if somebody actually has a working strategy or it's just gambling, they can be nearly indistinguishable, and (given the number of people) someone showing a streak of successes is really not much evidence that it's something beyond luck.
They may have something, but since you can't determine if it's so and there is a lot of just gambling, then most likely it's that.
That's part, but the reverse is also true. Someone could lose money and still have better odds than normal. Something like skill adds 5% then luck adds or removes 30%.
They may have something, but since you can't determine if it's so and there is a lot of just gambling, then most likely it's that.