Possibly he's just extremely lucky. There are seven billion people in the world - one of these people is almost certain to be luckier than all of the rest.

Possibly he is being looked after by a far more competent person behind the scenes; a spouse or a parent, perhaps, who dislikes being visible but works to help that person succeed.

Possibly that person really is more rational than you are, but his methods of success are so alien to you that your first instinct is to reject them out-of-hand.

Possibly his "writings" are actually being ghost-written by someone else.

Possibly he doesn't much care about what he writes, going for low-effort writing in order to concentrate on winning.

Possibly he's found one exploit that really works but won't work if everyone does it; thus, he keeps quiet about it.

Possibly he's deliberately writing to obscure or hide his own methods of success.

Possibly he's found a winning strategy, but he doesn't understand why it works, and thus invents a completely implausible "explanation" for it.

...have I missed anything?