This does not follow. You could just as easily argue that this means you are bad at predicting billionaires. YC is 8 for 1000 in the billionaire prediction game. Maybe that is good enough to claim expertise, but I think you have to actually make that argument and not assume it.

If the key to becoming a billionaire — the defining feature of billionaires — was to exploit people, then I, as a professional billionaire scout, would surely realize this.

This does not follow. First, "if this was true, I would know" is not an argument. Second, if exploitation is necessary, but not sufficient, it might be essentially useless as a predictor while still being universal among billionaires.