Sure, but when that moment happens over 20 years after you've started your "way of doing things", and you've amassed a giant fortune in the process, your eye-opening moment is not, "Well, I guess I was lucky all those years." Your eye-opening moment is, "Well, it's time to retire my strategy and change my methodology, if I can."
Nothing lasts forever. Conditions change in every arena of competition, not just the market. If a professional basketball player is incredibly successful until their bodies literally begin to degrade, do we raise philosophical questions about the inherent attribution of their skill?
People don't seem to respond well to the quant fund examples, so how about this - how has Warren Buffett consistently beat the market through Berkshire Hathaway? If he ceased beating the market this year, would it because he has been lucky all these years? Would it be because the market conditions that supported his success have fundamentally changed? If so, why does that indicate his performance was due to chance?