The key to me, it seems, would be to evaluate his decision making process as opposed to merely examining the outcome. If the stated rationale used at the outset

The key to me, it seems, would be to evaluate his decision making process as opposed to merely examining the outcome. If the stated rationale used at the outset is validated (repeatedly), then it stands to reason his success is due to more than simply being lucky. I'm not very familiar with Warren Buffet or the world he operates in, but my understanding is that he does not in fact take particularly risky stakes and explicitly stays away from verticals he's not familiar with. Hence my personal opinion would be that how he "thinks and acts" has directly contributed to his success - but happy to be proven wrong.